A heavy mortar is a large-calibre, short-barrelled weapon that projects a relatively heavy explosive projectile on a steep, high-angle trajectory. Designed to deliver plunging fire at close to medium ranges, heavy mortars trade range and flat-trajectory accuracy for the ability to hit targets protected by terrain or fortifications. They are generally simpler mechanically than equivalent-calibre field guns and are often used where indirect, high-arc fire is required.

Characteristics

Typical features include a short, robust barrel mounted on a baseplate or mount, and a mechanism to absorb recoil and direct the weapon. Heavy mortars commonly fire separate-loading charges and bombs or fin-stabilized rounds, and are operated by a crew that handles aiming, loading and charge selection. Ammunition types most often include high-explosive, smoke, illumination and, in some eras, chemical rounds. Compared with field artillery, heavy mortars have simpler aiming systems, lower muzzle velocity and a steeper angle of fall.

History and development

Mortars trace their lineage to medieval siege weapons that lobbed heavy projectiles into fortifications. In industrialized warfare their role expanded: during World War I the term "trench mortar" came to describe a range of heavy and medium mortars developed to attack entrenched positions and wire obstacles. The interwar and World War II periods saw refinements in mobility, sighting and ammunition. Postwar armies retained heavy infantry mortars for close support and developed vehicle-mounted and towed variants to improve tactical mobility.

Uses and examples

Heavy mortars are used primarily for close infantry support, bunker and trench suppression, and engaging targets in defilade where direct-fire weapons cannot reach. They are valued for rapid, steep-angle delivery of explosive effects and for relatively low logistical complexity compared with large artillery pieces. Examples of employment include trench assaults, urban fighting, and assaulting fortified positions. For broader context on mortar families and tactical employment see mortars overview and references on infantry support weapons at weapons reference.

Types and distinctions

  • Trench and siege mortars: historically used to batter fortifications and trenches; prominent in early 20th-century conflicts. See material on World War I trench mortars.
  • Infantry heavy mortars: man-portable at the unit level or transported by vehicle to provide immediate indirect fire support.
  • Vehicle-mounted/towed mortars: increase mobility and allow integration with armored formations.

Heavy mortars should be distinguished from field artillery, which generally fires flatter trajectories at longer ranges and uses more complex aiming and fire-control systems, and from rocket artillery, which uses unguided rockets to deliver high volumes of fire. Further technical and historical discussion is available in specialist sources: see artillery comparisons and archival material on early 20th-century mortars.