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Plunging fire

Plunging fire is fire employed in military tactics, characterized by projectiles descending at a steep angle onto targets, typically achieved through high-angle trajectories, indirect fire, or firing from elevated positions over lower terrain.^[1] This technique confines the danger space—the area in which rounds pose a threat—to the beaten zone, the elliptical pattern where projectiles impact the ground, making it effective for engaging targets in defilade or protected positions unreachable by direct, flat-trajectory fire.^[2] Common in machine guns, mortars, and artillery, plunging fire maximizes impact against dug-in infantry, reverse-slope defenses, or concealed enemies by allowing rounds to drop nearly vertically, bypassing obstacles like hills, trenches, or urban structures.^[3] In small arms and machine gun applications, plunging fire is obtained when engaging at long ranges (e.g., beyond 800 meters for 7.62mm weapons) or across elevation changes, such as from high ground to low or vice versa, where the arc of the trajectory limits the spread of effective fire to the target area. For mortars, it leverages their inherent high-angle design to deliver rapid, responsive support, outranging direct-fire weapons and penetrating cover in varied terrains like jungles, mountains, or urban environments, with minimum ranges as short as 70 meters enabling close protective fires.^[3] Artillery variants extend this capability to greater distances, using plunging trajectories for suppressive or destructive effects against fortifications.^[4] Historically, plunging fire traces back to ancient Near Eastern Bronze Age chariot warfare, where archers loosed high-trajectory arrows into the middle and rear ranks of infantry phalanxes to disrupt formations before charges.^[5] In modern conflicts, it gained prominence during World War I with Vickers machine guns delivering indirect plunging fire up to 4,500 yards for suppression, and in World War II, mortars provided plunging support in assaults like Cherbourg in 1944.^[3] Its enduring value lies in enhancing maneuver units' lethality by neutralizing threats in depth, particularly in defensive operations or urban combat, while minimizing exposure of firing positions.^[6]

Definition and Principles

Definition

Plunging fire is a form of indirect fire in which projectiles are launched along a high-angle trajectory, causing them to descend steeply onto the target from above; this technique is typically employed from elevated firing positions or at longer ranges where direct line-of-sight is obstructed.^[7] Key characteristics include a steep angle of fall that confines the danger space primarily to the beaten zone—the elliptical area on the ground where the majority of rounds impact—and enables engagement of defilade targets, such as those on reverse slopes or behind rising terrain. Unlike direct fire, which uses a relatively flat trajectory with the target serving as the point of aim and requires an unobstructed line of sight, plunging fire allows projectiles to arc over obstacles.^[8] It also contrasts with grazing fire, where the projectile path skims low over the ground at shallow angles, maintaining a low trajectory close to the surface throughout the range.^[7] This firing method is governed by ballistic principles that determine the projectile's arc and descent, though the underlying physics are explored in greater detail elsewhere. Common weapons systems utilizing plunging fire include artillery and mortars for high-volume, indirect support; machine guns and small arms such as rifles when fired from advantageous heights.^[9]

Ballistic Trajectory

Plunging fire relies on a parabolic ballistic trajectory that results in a steep angle of fall, often achieved with elevation angles greater than 45° in indirect fire but also at long ranges or with significant elevation differences in direct-fire weapons, causing the projectiles to follow a high-arcing path that descends steeply onto the target due to the dominant influence of gravity after the apex of the flight.^[10]^[7] This steep descent, known as the angle of fall, distinguishes plunging fire from direct or low-angle fire, enabling projectiles to impact from above and potentially bypass low cover. For indirect fire weapons like mortars, this typically involves elevations exceeding 45°; for machine guns and small arms, it arises from long ranges or elevation differences even at lower elevations. In the absence of air resistance, the trajectory is symmetric, with the angle of fall equaling the launch elevation angle, but atmospheric drag typically renders the descent steeper, enhancing the plunging effect.^[11] Several key factors influence the angle of fall in plunging fire. Higher muzzle velocity allows for greater range at a given elevation but can result in a less steep angle of fall unless compensated by increased elevation; conversely, lower velocities necessitate higher elevations for the same range, amplifying the plunging characteristic.^[11] Longer ranges exacerbate the curvature of the trajectory, increasing the angle of fall as gravity acts over extended time, while shorter ranges yield shallower descents.^[11] Additionally, an elevation difference between the firing position and target—such as firing from high ground to low—intensifies the plunging effect by effectively steepening the impact angle relative to the target's surface.^[9] In plunging fire, the cone of fire—the dispersion pattern of projectiles originating from the weapon—interacts with the ground to form a beaten zone, the elliptical area on the terrain where the majority of rounds impact. Unlike grazing fire, where the beaten zone is elongated horizontally, plunging fire confines the danger space—the region posing a casualty risk—primarily to the vertical confines of the impact area, with reduced horizontal spread due to the near-vertical trajectory. This vertical concentration enhances effectiveness against targets in defilade but limits the zone's lateral coverage.^[9] The time of flight for the ascent phase of the trajectory, until the projectile reaches its maximum height, is given by the equation

t = \frac{v \sin \theta}{g},

where v is the initial muzzle velocity, \theta is the elevation angle, and g is the acceleration due to gravity (approximately 9.81 m/s²). This time represents the duration over which the vertical component of velocity decreases to zero under gravity's influence.^[10] The full time of flight to impact, assuming level ground and negligible drag, is twice this value, $2t, leading to a symmetric descent. The angle of fall \phi, the angle below the horizontal at which the projectile strikes the target, equals \theta exactly in vacuum conditions due to trajectory symmetry. In real artillery scenarios with drag, computational firing tables adjust this for steeper falls at high angles.^[10]^[11]

Historical Development

Pre-20th Century Origins

The concept of plunging fire, characterized by high-angle trajectories to deliver projectiles onto targets from above, has roots in ancient warfare. In the Near Eastern Bronze Age, chariot archers employed high-trajectory arrow volleys into the middle and rear ranks of enemy infantry phalanxes to disrupt formations before charges, allowing projectiles to arc over front lines and strike protected troops. This tactic, seen in battles involving Hittite, Egyptian, and Mesopotamian forces around 1500–1200 BC, marked an early use of indirect fire to bypass shields and dense formations.^[5] In ancient times, Roman engineers employed stone-throwers and onagers, torsion-powered catapults capable of launching heavy stone balls (up to 26 kg) in high-arcing paths over walls to strike defenders or structures within. These machines, assembled on-site for sieges like that of Masada in AD 74, achieved ranges of up to 500 meters by adjusting elevation, marking an early form of indirect fire to exploit defensive elevations.^[12] During the medieval period, counterweight trebuchets refined this approach, hurling boulders of 45-90 kg over distances exceeding 275 meters to lob projectiles into fortified interiors, igniting fires or demoralizing garrisons behind walls. Introduced in Western Europe by the late 12th century, these engines were pivotal in sieges such as Toulouse in 1218, where massive counterweights enabled steep trajectories that evaded direct line-of-sight defenses. Mounted on towers or earthworks, trebuchets allowed attackers to target unshielded areas, transitioning from wall-breaching to overhead suppression tactics.^[13]^[14] Theoretical underpinnings for precise high-angle fire emerged in the 18th century through Benjamin Robins' ballistic experiments, detailed in his 1742 work New Principles of Gunnery. Using a ballistic pendulum to measure projectile velocities and accounting for air resistance, Robins' studies on curved trajectories laid the groundwork for calculating elevations needed for plunging shots, influencing gunnery tables for indirect aiming.^[15] In the 19th century, rifled artillery and elevated positions enabled practical applications of plunging fire against entrenched foes, as seen in the Crimean War (1853-1856) where Russian forces at Sevastopol used signaling systems for indirect bombardment from high ground to hit exposed British troops. This evolved further during the American Civil War, with Confederate Sergeant Milton W. Humphreys pioneering systematic indirect fire in 1862 at the Battle of Fayetteville, elevating his gun behind a ridge to arc shells over terrain onto Union artillery—a first in combat that demonstrated the tactic's potential against concealed targets.^[16]^[17] By the late 1800s, military doctrines formalized plunging fire as a counter to entrenched positions, with advancements in metallurgy and rifling improving shell stability for high-angle shots; U.S. and European manuals began incorporating it alongside early machine guns like the Gatling for overhead suppression. This recognition, driven by the need to protect guns from rifle fire, marked the shift toward modern indirect tactics without direct visibility.^[18]

World War I Applications

During World War I, plunging fire became integral to the tactics of static trench warfare on the Western Front, where machine gun platoons positioned on elevated terrain employed indirect high-angle trajectories to suppress enemy positions on reverse slopes that were shielded from direct line-of-sight fire. This technique allowed gunners to arc bullets over crests or obstacles, creating beaten zones that neutralized cover and movement without exposing the firing positions. German forces exemplified this at the Battle of Verdun in 1916, where machine guns on dominant heights delivered plunging fire to interdict French reinforcements and defenses in the Meuse valley, contributing to the prolonged attrition of the static front.^[19]^[20] Artillery applications of plunging fire were equally transformative, with high-angle howitzers firing shells on steep trajectories to penetrate dugouts, barbed wire entanglements, and fortified positions that flat-trajectory field guns could not effectively reach. The British introduced creeping barrages at the Battle of the Somme in 1916, where a rolling curtain of high-explosive shells—incorporating plunging elements from howitzers—advanced ahead of infantry assaults to suppress German defenses and clear paths through no-man's-land. This method marked a shift toward coordinated fire support, though initial implementations suffered from synchronization issues and incomplete destruction of wire, leading to heavy infantry losses.^[21]^[22] Innovations in plunging fire doctrine included the development of indirect fire tables for machine guns, which provided gunners with pre-calculated elevation and range data to enable accurate overhead fire without visual observation of targets. These tables, based on ballistic charts and terrain surveys, allowed for planned barrages similar to artillery. A notable early example of coordinated plunging suppression came from Canadian forces at the Battle of Vimy Ridge in April 1917, where machine gun harassing fire—delivered indirectly to disrupt German assembly areas and communications—supported the assault, with Vickers guns firing nearly 1.5 million rounds in the preparatory phase to thicken the artillery barrage and pin down defenders.^[23]^[24]^[25] The tactical employment of plunging fire significantly amplified casualty rates in prolonged engagements, as it denied troops effective cover and forced exposure to sustained suppression. At the Battle of Passchendaele in late 1917, German machine gun and artillery plunging fire from elevated ridges neutralized British and Canadian advances amid the mud-choked terrain, contributing to over 300,000 Allied casualties in the Third Battle of Ypres by saturating reverse slopes and shell holes where soldiers sought refuge. This high-attrition role underscored plunging fire's defensive potency in static warfare, where it turned natural features into lethal kill zones.^[26]^[24]

World War II and Postwar Evolution

Allied forces, facing entrenched Japanese positions in the Pacific theater, relied heavily on mortar teams for plunging fire to target cave networks. At Iwo Jima in 1945, U.S. Marine 60mm and 81mm mortars provided close-support plunging fire within 30-50 yards of forward lines, neutralizing cave entrances and suppressing defenders during assaults on Hills 362A and 362B. For instance, on March 2 (D+11), the 3rd Battalion, 9th Marines used these mortars alongside flamethrowers and grenades to dislodge Japanese from fortified ridges, while ammunition shortages often limited barrages to critical moments, forcing crews to scavenge shells from beaches. This high-angle fire was essential against the island's volcanic terrain, where direct fire was obstructed, complementing naval gunfire but proving vital for infantry advances into concealed positions.^[27] In naval warfare, plunging fire emphasized long-range gunnery to penetrate carrier decks during Pacific carrier battles. Although the Battle of Midway in June 1942 was primarily an air engagement, U.S. dive bombers like the Douglas SBD Dauntless executed plunging attacks that struck Japanese carriers such as Akagi and Kaga at steep angles, detonating on flight decks and igniting fueled aircraft below. This aerial variant of plunging fire mirrored surface gunnery principles, where high-angle trajectories bypassed side armor to exploit thinner horizontal protection, a vulnerability highlighted in subsequent actions like the Battle of the Philippine Sea. Postwar, plunging fire integrated into NATO doctrines during the Cold War, emphasizing defensive employment from elevated terrain to deny Soviet advances in Europe. U.S. Army field manuals, influential in NATO training, defined plunging fire as trajectories arcing over obstacles or from high to low ground, using machine guns and mortars for area suppression in mechanized infantry operations. This approach retained World War II lessons, prioritizing indirect fire to cover defilades and support linear defenses along the inner German border. In the Vietnam War, plunging fire remained relevant in irregular terrain, as seen at the Battle of Long Tan on August 18, 1966, where Viet Cong forces used machine guns from the elevated Nui Dat 2 feature to deliver plunging fire on Australian positions, sweeping broad areas through rubber plantations despite visibility limitations. Australian D Company, 6th Battalion, Royal Australian Regiment, countered with artillery and small-arms fire, but the engagement underscored plunging fire's role in high-ground dominance during ambushes. Technological advancements in the late 20th and early 21st centuries, particularly precision-guided munitions like the U.S. Army's M982 Excalibur (introduced in 2007), reduced reliance on traditional plunging fire by enabling direct, low-collateral strikes over long ranges, transforming artillery from area-suppression tools to pinpoint weapons. However, plunging fire persisted in low-tech conflicts, such as insurgencies, where unguided mortars and machine guns from elevated positions offered cost-effective suppression without advanced targeting systems.^[28]

Applications in Land Warfare

Machine Guns and Small Arms

Plunging fire with machine guns involves employing heavy crew-served weapons in an indirect mode, where the trajectory arcs over obstacles to strike targets from above, typically using elevated tripod mounts to achieve the necessary angle. This technique was notably applied with the British Vickers .303 machine gun during both World Wars, where guns were positioned on stable tripods and aligned using dial sights for precise elevation and azimuth adjustments, enabling ranges up to 4,500 yards with specialized Mark VIIIz ammunition.^[23] The German MG42 general-purpose machine gun was similarly adapted for indirect plunging fire in defensive roles, particularly when mounted on the Lafette 42 tripod, allowing gunners to engage obscured or distant targets by elevating the barrel to create a high-angle trajectory.^[29] Effective execution requires spotters to observe impacts and forward corrections, along with precomputed fire adjustment tables based on range, wind, and elevation data to account for ballistic drop.^[23] For small arms, plunging fire is achieved by individual riflemen or squads firing from elevated positions onto lower ground, exploiting the natural arc of the bullet's trajectory at extended ranges of approximately 500 to 800 meters. U.S. Army doctrine in FM 3-22.68 outlines this application in high-to-low ground scenarios, where rifle fire transitions from direct to plunging as terrain drops away, confining the danger space to the beaten zone and limiting grazing coverage.^[2] This method was particularly useful in defensive positions overlooking valleys or slopes, allowing infantrymen with rifles like the M1 Garand or later 7.62mm systems to suppress enemy movements without line-of-sight exposure. Training for plunging fire emphasizes the use of specialized long-range sights, such as the British Vickers Dial Sight Mk III or U.S. M1918 panoramic sights, which incorporate clinometers and scales for measuring elevation angles and compensating for arc fire. These optics enable gunners to align on pre-registered targets, but the confined beaten zone in plunging trajectories reduces effectiveness against moving targets, as bullets impact in a narrower vertical spread compared to grazing fire.^[30] Military manuals stress repetitive range practice to master sight adjustments and burst control, ensuring crews can maintain sustained fire without overheating barrels.^[2] In practice, plunging fire with machine guns and small arms faces significant limitations, including high ammunition consumption due to the need for volume to compensate for dispersion over distance—Vickers barrages often required thousands of rounds per minute across multiple guns.^[23] Accuracy degrades without forward observers to relay adjustments, leading to ineffective beats on unregistered targets, and the technique's reliance on static positions makes it vulnerable to counter-battery fire or flanking maneuvers.^[2]

Artillery and Mortars

Mortars are indirect fire weapons inherently designed for high-angle plunging fire, with trajectories typically ranging from 45 to 90 degrees, enabling them to deliver close support against targets in defilade or behind obstacles.^[31] This steep angle of fall allows mortars to engage enemy positions such as reverse slopes, urban structures, or trenches that are shielded from direct fire, providing rapid suppressive effects with high-explosive rounds.^[3] In U.S. Marine Corps tactics, particularly during urban combat operations, mortar employment emphasizes overhead clearance to ensure safe trajectories over friendly forces and obstacles, with positions selected in open areas like parking lots or parks to avoid mask interference from buildings.^[32] For instance, an 81-mm mortar fired at elevations exceeding 885 mils requires approximately one-quarter of a building's height setback for clearance near structures, minimizing risks from premature detonations or counterfire.^[3] Field artillery howitzers, such as the WWII-era 105-mm M2A1, incorporate adjustable elevations up to 66 degrees (1,156 mils) to execute plunging barrages, allowing precise delivery of shells onto reverse-slope positions beyond line-of-sight.^[33] These systems use variable propellant charges—up to seven increments—to control trajectory height and range, enabling high-angle fire that exploits terrain cover against entrenched foes, as seen in European and Pacific theaters where the M2A1 supported infantry advances by neutralizing hidden defenses.^[33] Unlike mortars, howitzers balance plunging and flat-trajectory capabilities, making them suitable for both close and extended engagements in combined arms operations. Fire direction for plunging fire relies on forward observers to locate targets, adjust rounds via bracketing or creeping techniques, and account for vertical confinement in danger space—the zone where projectile dispersion poses a threat regardless of minor range errors—to effectively target defilade positions.^[34] Observers transmit corrections in mils for deviation and meters for range, often using laser rangefinders for precision, while "danger close" procedures limit adjustments to 100 meters when friendly troops are within 600 meters of impact to mitigate risks.^[34] This process ensures plunging rounds maintain lethality against concealed targets, with the vertical danger space aiding confinement to specific elevations like hill crests or building tops. In terms of comparative ranges, mortars provide effective plunging support up to approximately 5 kilometers with 81-mm systems, while field artillery howitzers extend this to over 20 kilometers in modern variants, though WWII 105-mm models achieved about 11 kilometers, allowing deeper strikes against rear areas.^[3]^[33]

Naval Applications

Long-Range Surface Gunnery

In naval surface gunnery, plunging fire refers to artillery shells fired at long ranges, typically 15 kilometers or greater, where the projectiles descend at steep angles of 15 to 40 degrees or more, enabling them to penetrate a target's horizontal deck armor rather than its thicker vertical side armor.^[35] This contrasts with direct or flat-trajectory fire at closer ranges, which primarily impacts the belt armor along the hull sides. The effectiveness of plunging fire depends on the shell's trajectory achieving sufficient vertical incidence to defeat deck plating, typically 1 to 3 inches thick on pre-World War II designs, while avoiding deflection from angled surfaces.^[36] Key ballistic factors influencing plunging fire include the gun's muzzle velocity, barrel elevation, and projectile weight, which determine the angle of fall at extended ranges. High-velocity naval guns, such as the 16-inch/50-caliber Mark 7 mounted on the Iowa-class battleships, achieve plunging trajectories by elevating to 45 degrees, yielding a maximum range of approximately 38.7 kilometers with an angle of fall around 51 degrees for armor-piercing shells.^[37] Range tables, derived from empirical testing and ballistic computations, predict these fall angles; for instance, at 25 to 30 kilometers, a 16-inch shell falls at 21 to 28 degrees, sufficient to perforate up to 250 millimeters of horizontal armor under optimal conditions.^[35] These tables were integral to fire control systems, allowing gunners to adjust for variables like wind and target motion to maximize deck hits.^[37] Tactically, plunging fire played a critical role in surface naval combat by enabling engagement at standoff distances beyond 15 kilometers, reducing exposure to close-quarters torpedo or secondary battery threats while exploiting enemy deck vulnerabilities.^[38] British World War II doctrines, as outlined in the 1939 Fighting Instructions, emphasized plunging fire for capital ships in long-range duels, prioritizing offensive positioning to force opponents into ranges where deck penetration was likely, though commanders often sought to close distances to negate this risk for their own vessels.^[39] This approach influenced fleet dispositions, with battleships like those of the King George V class designed to withstand plunging impacts up to 30 kilometers.^[40] A notable vulnerability exploited by plunging fire was the inadequate deck armor on older battlecruisers, such as HMS Hood, whose 3-inch decks offered limited protection against heavy shells at long ranges. During the Battle of the Denmark Strait on May 24, 1941, Hood was sunk by plunging fire from the German battleship Bismarck at around 18 kilometers, where a 15-inch shell penetrated the thin deck plating and detonated in the magazines, leading to a catastrophic explosion.^[41] This incident underscored the dangers of outdated designs against modern plunging trajectories, prompting postwar reevaluations of horizontal armor schemes in naval architecture.^[42]

Air-Launched Variants

Air-launched variants of plunging fire emerged prominently in World War II dive bombing tactics, where aircraft executed steep descents to deliver ordnance along gravity-assisted trajectories for enhanced accuracy against naval targets. The German Junkers Ju-87 Stuka, for instance, typically dove at an 85-degree angle, using perforated dive brakes to stabilize the aircraft and align the bomb's path nearly vertically with the target below, maximizing penetration through deck armor. This method relied on gravitational acceleration to accelerate the bomb along a near-straight line after release, reducing ballistic dispersion compared to level bombing.^[43] Similarly, U.S. Navy Douglas SBD Dauntless aircraft at the Battle of Midway in 1942 utilized near-vertical dives, approaching targets from 15,000 feet at a 70-degree flight path angle to achieve plunging impacts on Japanese carriers. Pilots released 1,000-pound bombs at around 1,500 feet, where gravity had imparted sufficient velocity—up to 300 knots—for the munitions to punch through flight decks and ignite fueled aircraft below, sinking four carriers in minutes despite heavy antiaircraft fire. The physics of these dives exploited the bomb's inheritance of the aircraft's forward velocity while gravity dominated the vertical component, ensuring a predictable, high-angle terminal trajectory.^[44] Postwar developments in precision-guided munitions have refined air-launched plunging fire, incorporating guidance systems to replicate and improve upon WWII high-angle deliveries against ships and fortified bunkers. The Joint Direct Attack Munition (JDAM), for example, allows configurable vertical terminal trajectories via GPS/INS, enabling steep dives for deep penetration into hardened structures or vessel hulls, with circular error probable as low as 2 feet in tests. Modern variants like the QUICKSINK, a laser seeker-enhanced JDAM, further adapt this by fusing imaging infrared for terminal homing, allowing B-2 bombers to execute high-angle attacks that detonate below a ship's waterline, as demonstrated in September 2025 tests sinking a target vessel at long ranges. These systems enhance plunging accuracy in all weather, prioritizing vertical impact angles over 60 degrees to defeat armor while minimizing collateral damage.^[45]^[46]

Tactics and Employment

Defensive and Offensive Uses

In defensive tactics, plunging fire is strategically employed from elevated positions to deny enemy avenues of approach and create prohibitive kill zones. Machine gun nests situated on hills or ridges deliver high-angle trajectories that confine the danger space to the beaten zone, effectively turning open terrain into a no-man's-land where advancing forces face concentrated, suppressive fire with limited grazing coverage. This approach leverages defilade for gunner protection while maximizing impact on low-lying enemy movements.^[2]^[1] A notable example occurred during the Battle of Iwo Jima in 1945, where Japanese defenders integrated plunging machine gun fire from high ground positions around Mount Suribachi and the island's rugged northern ravines to enfilade and halt Marine advances, inflicting severe casualties on exposed assault waves.^[47]^[48] Offensively, plunging fire supports maneuver by suppressing rear areas and enemy positions obscured by terrain, enabling combined arms integration where infantry assaults follow protective barrages. Machine guns or mortars positioned on higher ground deliver arcing trajectories to neutralize threats behind crests or depressions, disrupting enemy cohesion and facilitating rapid advances. In ambush scenarios, this tactic traps targets in confined spaces, with fire from elevated vantage points overwhelming columns below.^[2] During the Vietnam War, North Vietnamese ambushes frequently utilized plunging fire from machine guns on higher terrain, as seen in engagements where elevated positions peppered U.S. patrols with automatic weapons fire, exploiting the terrain to pin and destroy forces in low ground.^[49] Effective planning for plunging fire requires thorough terrain analysis to select high ground that optimizes trajectories and observer lines of sight, while coordinating fire support to synchronize with broader operations. U.S. Army doctrine in FM 3-22.68 stresses recording minimum elevations on range cards, adjusting for masks like hills, and employing observers for precise shifts, ensuring the technique's confinement to the beaten zone enhances both defensive denial and offensive suppression.^[2]^[1]

Advantages and Limitations

Plunging fire offers significant advantages in engaging targets obscured by terrain or fortifications, as it enables projectiles to arc over obstacles such as hill crests or reverse slopes, striking enemies in defilade positions that direct fire cannot reach.^[50] This capability is particularly valuable for howitzers and machine guns positioned in defilade, providing the firing unit with cover and concealment from enemy direct-fire weapons while allowing partial obscuration of muzzle flash and smoke.^[51] Additionally, it concentrates effects within the beaten zone at long ranges or over uneven ground, maximizing impact on specific areas like trenches or elevated cover where grazing fire proves ineffective.^[6] Despite these benefits, plunging fire has notable limitations that can compromise its utility in dynamic engagements. The steep trajectory confines the danger space to the beaten zone, eliminating the continuous suppressive effect along the gun-target line that grazing fire provides, and demands precise adjustments that are challenging against fast-moving or dispersed targets.^[2] Accuracy diminishes at extreme angles due to factors like wind drift and the need for observer-dependent corrections, while targets near the masking terrain cannot be engaged effectively.^[51] For artillery applications, the elevated firing positions required often increase exposure to counter-battery fire, as the unit's location becomes more predictable to enemy observers.^[3] High ammunition consumption further strains logistics, especially in sustained suppressive roles, as the technique relies on volume to compensate for reduced precision.^[6] In comparative terms, plunging fire excels over grazing fire when bypassing line-of-sight obstacles or hitting defilade, but it falls short in delivering the high-volume, low-angle coverage of direct fire, which maintains broader danger spaces and simpler adjustments on open terrain.^[2] These limitations can be mitigated through reliance on forward spotters for real-time fire adjustments and rigorous crew training in elevation and traverse mechanisms, which enhance accuracy and reduce wasteful expenditure in both machine gun and artillery contexts.^[51]^[6]

Modern and Contemporary Tactics

In contemporary military operations, plunging fire has been enhanced through integration with precision-guided technologies, enabling high-accuracy high-angle trajectories against obscured targets. The M982 Excalibur, a GPS- and inertial-guided 155 mm artillery round, exemplifies this advancement by providing precise plunging fire capable of engaging defiladed positions with a circular error probable of less than 2 meters at ranges up to 40 kilometers, as demonstrated in U.S. Army tests for indirect fire support.^[52]^[53] In the ongoing Russo-Ukrainian War since 2022, Ukrainian forces have employed commercial and military drones as forward spotters to correct artillery and mortar fire, significantly improving the effectiveness of plunging trajectories in contested terrain; these drone-corrected strikes have allowed for rapid adjustments, reducing the number of rounds needed for target neutralization and countering Russian advances in areas like Donbas.^[54] In asymmetric conflicts, non-state actors have adapted plunging fire using improvised or low-tech systems to conduct high-angle attacks on fortified positions. During the U.S.-led intervention in Afghanistan from 2001 to 2021, Taliban insurgents frequently employed captured, modified, or homemade mortars to launch indirect high-angle fire against coalition bases and outposts, exploiting the weapons' ability to arc projectiles over walls and terrain for surprise assaults on personnel and infrastructure in remote valleys.^[55] This tactic proved effective in low-intensity environments where insurgents lacked air support but could leverage mobility and terrain for hit-and-run engagements. U.S. Marine Corps doctrine continues to emphasize plunging fire in military operations in urban terrain (MOUT), where mortars' steep trajectories penetrate buildings and engage enemies in defilade with minimal collateral risk, as outlined in tactical manuals prioritizing organic indirect fire for close support in dense urban settings.^[32]^[3] However, the prevalence of air superiority in conventional operations has led to reduced reliance on traditional plunging fire in favor of precision airstrikes, though it remains a core capability for low-tech, contested, or denied-airspace scenarios to ensure responsive, survivable fire support.^[56] Looking ahead, hypersonic weapons may revive long-range plunging fire concepts by combining high-speed glide trajectories with maneuverability, allowing for rapid, unpredictable high-angle descents on defended targets and enabling synchronized deep strikes in peer conflicts.^[57]^[58]

References

[1]
None
### Definition and Explanation of Plunging Fire
[2]
FM23-22.68 Chapter 5 Combat Techniques of Fire
Plunging fire occurs when the danger space is confined to the beaten zone. Plunging fire also occurs when firing at long ranges, from high ground to low ground, ...
[3]
None
Below is a merged summary of "Plunging Fire in Mortars" from MCWP 3-15.2, consolidating all information from the provided segments into a single, comprehensive response. To maximize detail and clarity, I’ve organized the key information into a table in CSV format, followed by a narrative summary that integrates additional context and historical notes. This ensures all details are retained while maintaining readability.
[4]
https://www.armyupress.army.mil/Portals/7/combat-studies-institute/csi-books/AOW/AoW_Paris_Gun_Trap_book_and_covers_WEB.pdf
[5]
Chariot Tactics in the Near Eastern Bronze Age
Instead they would direct high trajectory fire into the middle and rear ranks, thereby endeavoring to weaken the infantry mass through plunging fire. When the ...
[6]
[PDF] Machine Gun Marksmanship - Army Reserve
Plunging Fire. Plunging fire occurs when there is little or no danger space from the muzzle to the beaten zone, thus the weapon's effect is limited to ...
[7]
FM 23-65 Chptr 6 Combat Techniques of Fire - GlobalSecurity.org
Plunging fire is obtained when firing from high ground to low ground ... Grazing fire is fire in which the center of the cone of fire does not rise ...
[8]
direct fire (US DoD Definition) - Military Factory
Fire delivered on a target using the target itself as a point of aim for either the weapon or the director. (JP 3-09.3) (US DoD) ...<|control11|><|separator|>
[9]
FM 23-27 Chptr 6 Techniques of Fire - GlobalSecurity.org
Plunging fire strikes the target from a high angle and confines the danger space to the beaten zone. For example, when fired from the top of a hill, projectiles ...
[10]
4.3 Projectile Motion – General Physics Using Calculus I
Find the time of flight and impact velocity of a projectile that lands at a different height from that of launch. Calculate the trajectory of a projectile.
[11]
FIRE CONTROL FUNDAMENTALS - Part C
These lines make equal angles with the horizontal, so that the angle of departure (elevation angle Eg) equals the angle of fall. In the case illustrated, when ...
[12]
Ancient Artillery - Antigone Journal
Oct 6, 2024 · Stone-throwers threw heavy stone balls, usually in a high trajectory – in other words indirect fire. They were initially used in siege warfare ...
[13]
Artillery in Medieval Europe - World History Encyclopedia
May 28, 2018 · Distance and angle of fire could both be improved by putting a machine on a hill or even a tower, as happened in conflicts in Italian towns ...Missing: high | Show results with:high
[14]
Collections: The Siege of Eregion, Part III: What Catapults?
Mar 14, 2025 · Now it is the case that during medieval sieges, attackers might intentionally use the high firing arc of trebuchets to fire over the walls, ...
[15]
Benjamin Robins (1706 - 1751) - Biography - MacTutor
Robins invented the ballistic pendulum which allowed precise measurements of the velocity of projectiles fired from guns. As described by Robins, a large wooden ...Missing: plunging fire
[16]
[PDF] Field Artillery: The Evolution of Indirect Fire Methods
In the siege of Sevastopol during the Crimean War the Russians used some very good systems of signalling to enable fortress artillery to hit British forces in ...Missing: tactics | Show results with:tactics
[17]
Sergeant Milton Humphreys' Concept of Indirect Fire - HistoryNet
Jun 12, 2006 · Eighteen-year-old Sergeant Milton Humphreys changed the nature of artillery forever with his concept of indirect fire.
[18]
[PDF] Direct Fire to Indirect Fire: Changing Artillery for the Future - DTIC
May 15, 2000 · introduction of indirect artillery fire during the late 1800s. Toward the end of the nineteenth century, advances in metallurgy, casting and.
[19]
What Was The Battle Of Verdun? | Imperial War Museums
French troops manning a captured German Maxim MG 08 machine gun (mounted on a sledge) at Fort Douaumont, Verdun. See object record. At 4am on 21 February 1916 ...
[20]
The Price of Glory: Verdun 1916 Reviewed by Bruce Sloan
Jan 14, 2014 · ... machine gun, which I believe wasn't issued until 1917? The gunner seems to be using plunging fire, presumably at a distant target, although ...
[21]
How the British artillery developed and became a war-winning factor ...
Jul 24, 2015 · Note that the howitzer has a higher arc of fire than a field gun, enabling its shell to plunge towards target. ... Somme in 1916. General ...Firing Accurately At The... · Firing At The Right Enemy · Organising To Fire At The...
[22]
The creeping barrage - Legion Magazine
Jun 4, 2015 · The idea of “lifting” fire forward in front of advancing troops was tried in 1915, but the optimum method was determined in 1916 during the ...
[23]
Indirect Fire: A Primer - Vickers MG Collection & Research Association
Jan 17, 2021 · DIRECT fire is targets that can be seen from the gun position; INDIRECT fire is for targets that are obscured.
[24]
Machine Gun - 1914-1918 Online
Dec 2, 2015 · By exploiting the curved trajectory followed by their bullets, machine guns could fire indirectly, like miniature artillery pieces – even over ...
[25]
[PDF] First World War Canadian Operational Research
Mar 27, 2023 · The machine gun barrage was an important component of the fire plan for the assault on Vimy Ridge in 1917, and. Brutinel's guns fired nearly ...
[26]
Battle of Passchendaele | National Army Museum
Jul 31, 2017 · The British suffered 300,000 casualties fighting for Passchendaele, and inflicted around 260,000 on the Germans. The British had taken the high ...Missing: plunging | Show results with:plunging
[27]
U.S. and German Field Artillery in World War II: A Comparison
They were also capable of plunging fire ... In World War II, both German and American artillery fire direction was normally done at the battalion level.
[28]
[PDF] Iwo Jima: Amphibious Epic - Marine Corps University
60mm mortar fire covered areas to within 30 yards of the lines to pin down and neutralize the enemy to the immediate front. Tanks and rocket launchers were ...<|separator|>
[29]
Battle of Long Tan - Wikipedia
With the help of strong artillery fire, D Company held off a regimental assault before a relief force of M113 armoured personnel carriers and infantry from Nui ...Harry Smith (Australian soldier) · 1st Australian Task Force · Oliver David Jackson
[30]
[PDF] Artillery in the digital age - Air Power Australia
The advent of advanced guided artillery ammunition fundamentally changes how artillery is used, and indeed when it can be used. For decades, artillery pieces ...
[31]
German MG 42 Indirect Fire Manual - English Translation - MG34
This manual explains why the scope can pivot fully around and how that is used for indirect fire. It's not specifically written as an MGZ manual.Missing: historical | Show results with:historical
[32]
MACHINE GUN FIRE CONTROL - Small Arms Review
Mar 1, 2012 · GRAZING FIRE – is fire delivered over the crest of a hill with an angle of fall conforming to the slope of the ground. PLUNGING FIRE ... 30 ...<|control11|><|separator|>
[33]
None
Below is a merged summary of the mortar fire characteristics for high-angle fire based on the provided segments from FM 23-90. To retain all information in a dense and organized manner, I’ve used tables in CSV format where appropriate, alongside narrative text for broader concepts. This response consolidates all details, including definitions, characteristics, equipment, applications, and references, while avoiding redundancy.
[34]
[PDF] Use of Mortars in Military Operations on Urbanized Terrain (MOUT)
Position selection should be open enough to allow full coverage of the sector of fire without mask or overhead interference at minimum ranges.
[35]
A Brief History of the M-101A1 105mm Howitzer - HistoryNet
Apr 17, 2018 · The 105's maximum elevation of 1156 mils (66 degrees/13 minutes) gave it a high-angle fire capability to engage reverse slope targets, critical ...
[36]
FM 6-30 Chapter 5 Adjustment Of Fire - GlobalSecurity.org
If the adjustment of fire moves the round outside the danger close distance, the observer transmits CANCEL DANGER CLOSE. Danger close distances are as follows: ...
[37]
Protection Against Bombs and High-Angle Shell Fire | Proceedings
(16 in.) would have an angle of fall of 25°-30°, striking the armor at an angle to the normal of 60°-65°.
[38]
Guns - The Pacific War Online Encyclopedia
Plunging fire is fire that comes in at a steep angle, so that the shells strike the deck of an enemy ship rather than the sides. In general, armored ships of ...
[39]
USA 16"/50 (40.6 cm) Mark 7 - NavWeaps
Oct 28, 2025 · At an "average gun" MV of 2,425 fps (1,739 mps), the maximum range with AP Mark 8 at a 40 degree elevation was 40,185 yards (36,745 m). The ...
[40]
Battles of Savo Island and Eastern Solomons
Price of the Wilson remarks, "Our cruisers appeared to be enveloped in a plunging fire as soon as they were illuminated." Capt. Riefkohl's order for an ...<|control11|><|separator|>
[41]
ADM 239/261- The Fighting Instructions (1939)
GENERAL. FIGHTING THE ENEMY 1. This can only be achieved by a strong offensive spirit and by bold and correct tactical handling of the units engaged.
[42]
[PDF] The Evolution of Fleet Tactical Doctrine in the USN 1922-1941
Norman Friedman's numerous design studies have shown that the Navy's battleships enjoyed a relatively high level of protection against plunging fire. Beginning ...
[43]
Channel 4 - Hood v Bismarck - History - The Battles - PBS
At that range, Hood was vulnerable to plunging shell fire. The British ship tried to close up on Bismarck so that any fire would hit her well-protected sides ...
[44]
The Loss of H.M.S. Hood: A Re-Examination - NavWeaps
Oct 5, 2025 · 'Prince of Wales' opened fire at 0553. 'Bismarck' replied with extreme accuracy on 'Hood.' 2nd or 3rd salvo straddled and fire broke out in ' ...
[45]
Remarks on Submarine Tactics Against Convoys
Nov 6, 2017 · When attacking a ship protected by an escort, the best position for the submarine to fire from is one in which her torpedo will travel at right ...
[46]
Gyro-angled torpedoes - Torpedo Vorhaltrechner Project
It was technically possible to use gyro-angled torpedoes during the Great War. Torpedoes were fitted with gyroscopes that allowed setting the angle of gyro- ...
[47]
The Stuka - Warfare History Network
One such aircraft was undoubtedly the German Junkers Ju-87 dive bomber. Known as the “Stuka” (an abbreviation of Sturzkampfflugzeug or “dive bomber”), the Ju-87 ...Missing: plunging | Show results with:plunging
[48]
Flightdeck Friday: Smoke and the Battle of Midway - USNI Blog
Sep 26, 2009 · Ideally the dive bombing aircraft, in a vertical 90 degree attitude, plunged at a 70 degree flight path because of the remaining lift on the ...
[49]
JDAM Matures Parts 1 and 2 - Air Power Australia
The flight control algorithm can be configured before launch for vertical or horizontal (ie shallow dive) terminal trajectories, selected by the user for a ...
[50]
USAF's Quicksink Ship-Killing Smart Bomb Seen In Detail Like ...
Sep 10, 2025 · “The B-2 played a central role, employing precision-guided QUICKSINK munitions to engage and sink the maritime target,” according to an Air ...
[51]
1/27 on Iwo - Marine Corps Association
Jun 15, 2025 · Enfilade fire from the high ground on the right and plunging fire from Mount Suribachi on the left pummeled the landing beaches and follow-on ...
[52]
Battle of Iwo Jima — Returning to the Black Sands - The Armory Life
Feb 19, 2024 · A view across the beach toward Mt. Suribachi. Plunging fire from ... Machine guns were sighted for deadly interlocking fire. Rockets ...
[53]
[PDF] Seven Firefights in Vietnam - U.S. Army Center of Military History
Oct 11, 1984 · Plunging through intense fire from the enemy, the jets dropped six high-drag SaO-pound bombs at the western edge of the ambush. Smith then ...
[54]
FM 23-65 Chptr 6 Combat Techniques of Fire - BiggerHammer
(1) Plunging fire. Fire in which the angle of fall of the rounds (with reference to the slope of the ground) is such that the danger space is confined to the ...<|control11|><|separator|>
[55]
404 Error
Insufficient relevant content. The provided URL (https://www.trngcmd.marines.mil/Portals/207/Docs/TBS/MCWP%203-15.2%20Tactical%20Employment%20of%20Mortars.pdf) results in a 404 error, indicating the page is not found. The error message states that the U.S. Marine Corps has migrated to a new platform, causing URL changes, and suggests using the search box, homepage, or common subjects list to find resources. No specific details on plunging fire or indirect fire advantages and limitations in mortar employment from MCWP 3-15.2 are available due to the inaccessible document.
[56]
Excalibur Projectile | Raytheon - RTX
The Excalibur is a precision, extended-range artillery projectile with a less than two meter radial miss distance, impacting at all ranges in all weather.
[57]
Artillery: December 2, 2004 - The Hundred Years War
Dec 2, 2004 · The US Army has successfully tested its new 155mm Excalibur guided artillery shell, showing that it can provide plunging fire against ...
[58]
Drones Give Ukraine's Grenade Machine Guns A Deadly New Trick
Dec 8, 2022 · Ukrainian artillery units now appear to be universally supplied with drone spotters, which has greatly increased their effectiveness. Ukrainian ...
[59]
https://www.wsj.com/world/ukraines-drone-spotters-on-front-lines-wage-new-kind-of-war-11659870805
[60]
Afghan firefight illustrates challenge for U.S. - Deseret News
Jun 22, 2009 · The vehicles were heading to inspect a suspected tunnel when the Taliban struck, firing mortars that landed close by. Machine gunners atop the ...
[61]
Air Supremacy Lost: An Imminent Danger for Ground Troops
After decades without enemy air threats, the Marine Corps had little incentive to invest in air-defense systems or train to operate under contested ...
[62]
https://warontherocks.com/2019/11/hypersonic-weapons-tactical-uses-and-strategic-goals/
[63]
Complex Air Defense: Countering the Hypersonic Missile Threat
Feb 9, 2022 · We look at hypersonic maneuvering reentry vehicles, hypersonic glide vehicles, and hypersonic cruise missiles. ... They have gliding scramjet ...<|separator|>