Indirect fire

indirectfall of shotindirect-fireindirect artillery fireIndirect fire supportdirect fireindirect artilleryartilleryfall of a warship's gunfirefall-of-shot
Indirect fire is aiming and firing a projectile without relying on a direct line of sight between the gun and its target, as in the case of direct fire.wikipedia
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Direct fire

directdirect-fireline of sight
Indirect fire is aiming and firing a projectile without relying on a direct line of sight between the gun and its target, as in the case of direct fire.
This is in contrast to indirect fire, which refers to firing a projectile on a ballistic trajectory or delivering munitions by guided or unguided missiles.

Mortar (weapon)

mortarmortarsspigot mortar
Handguns and rifles, machine guns, anti-tank guns, tank main guns, many types of unguided rockets (although missiles, mortars, howitzers, rocket artillery, multiple rocket launchers, and artillery in general, cruise missiles, and ballistic missiles, etc., are indirect), and guns mounted in aircraft are examples of weapons primarily designed for direct fire. Indirect fire is most commonly associated with field artillery (although field artillery was originally and until after World War I a direct fire weapon, hence the bullet-shields fitted to the carriages of guns such as the famous M1897 75 mm) and mortars.
Mortars are typically used as indirect fire weapons for close fire support with a variety of ammunition.

Artillery observer

forward observerartillery spottingForward Observation Officer
Aiming is performed by calculating azimuth and inclination, and may include correcting aim by observing the fall of shot and calculating new angles.
Spotters ensure that indirect fire hits targets which the troops at the fire support base cannot see.

Howitzer

howitzersHTowed howitzer
Handguns and rifles, machine guns, anti-tank guns, tank main guns, many types of unguided rockets (although missiles, mortars, howitzers, rocket artillery, multiple rocket launchers, and artillery in general, cruise missiles, and ballistic missiles, etc., are indirect), and guns mounted in aircraft are examples of weapons primarily designed for direct fire.
Because of this practice, the word "howitzer" is used in some armies as a generic term for any kind of artillery piece that is designed to attack targets using indirect fire.

Field artillery

field piecefieldtowed artillery
Indirect fire is most commonly associated with field artillery (although field artillery was originally and until after World War I a direct fire weapon, hence the bullet-shields fitted to the carriages of guns such as the famous M1897 75 mm) and mortars.
Most field artillery situations require indirect fire due to weather, terrain, night-time conditions, distance, or other obstacles.

Artillery

heavy artilleryordnanceartillery piece
Handguns and rifles, machine guns, anti-tank guns, tank main guns, many types of unguided rockets (although missiles, mortars, howitzers, rocket artillery, multiple rocket launchers, and artillery in general, cruise missiles, and ballistic missiles, etc., are indirect), and guns mounted in aircraft are examples of weapons primarily designed for direct fire.
In the next 15 years leading up to World War I, the techniques of indirect fire became available for all types of artillery.

Aiming point

aim point
These methods probably involved an aiming point positioned in line with the target.
In field artillery, the accuracy of indirect fire depends on the use of aiming points.

Gun laying

traversegun layergun-laying
It may be laying for direct fire, where the gun is aimed similarly to a rifle, or indirect fire, where firing data is calculated and applied to the sights.

Predicted fire

predictedpredicted artillery firesilent registration
Predicted fire was introduced in World War I.
Predicted fire aims to achieve tactical surprise when the target is to be engaged by indirect fire.

Prism paralleloscope

Its purpose was to function as an aiming point in the horizontal plane when laying for indirect fire artillery.

Azimuth

azimuthalazimuthal angleazimuth angle
Aiming is performed by calculating azimuth and inclination, and may include correcting aim by observing the fall of shot and calculating new angles.

Orbital inclination

inclinationinclinedtilted
Aiming is performed by calculating azimuth and inclination, and may include correcting aim by observing the fall of shot and calculating new angles.

Trajectory

trajectoriesflightpathflight path
The projectile trajectory is affected by atmospheric conditions, the velocity of the projectile, the difference in altitude between the firer and the target, and other factors.

Handgun

handgunspistolpistols
Handguns and rifles, machine guns, anti-tank guns, tank main guns, many types of unguided rockets (although missiles, mortars, howitzers, rocket artillery, multiple rocket launchers, and artillery in general, cruise missiles, and ballistic missiles, etc., are indirect), and guns mounted in aircraft are examples of weapons primarily designed for direct fire.

Rifle

hunting rifleriflesrevolving rifle
Handguns and rifles, machine guns, anti-tank guns, tank main guns, many types of unguided rockets (although missiles, mortars, howitzers, rocket artillery, multiple rocket launchers, and artillery in general, cruise missiles, and ballistic missiles, etc., are indirect), and guns mounted in aircraft are examples of weapons primarily designed for direct fire.

Anti-tank gun

anti-tankanti-tank gunsAT gun
Handguns and rifles, machine guns, anti-tank guns, tank main guns, many types of unguided rockets (although missiles, mortars, howitzers, rocket artillery, multiple rocket launchers, and artillery in general, cruise missiles, and ballistic missiles, etc., are indirect), and guns mounted in aircraft are examples of weapons primarily designed for direct fire.

Tank gun

gunmain gunmain guns
Handguns and rifles, machine guns, anti-tank guns, tank main guns, many types of unguided rockets (although missiles, mortars, howitzers, rocket artillery, multiple rocket launchers, and artillery in general, cruise missiles, and ballistic missiles, etc., are indirect), and guns mounted in aircraft are examples of weapons primarily designed for direct fire.

Rocket (weapon)

rocketrocketsunguided rocket
Handguns and rifles, machine guns, anti-tank guns, tank main guns, many types of unguided rockets (although missiles, mortars, howitzers, rocket artillery, multiple rocket launchers, and artillery in general, cruise missiles, and ballistic missiles, etc., are indirect), and guns mounted in aircraft are examples of weapons primarily designed for direct fire.

Missile

guided missilemissilesguided missiles
Handguns and rifles, machine guns, anti-tank guns, tank main guns, many types of unguided rockets (although missiles, mortars, howitzers, rocket artillery, multiple rocket launchers, and artillery in general, cruise missiles, and ballistic missiles, etc., are indirect), and guns mounted in aircraft are examples of weapons primarily designed for direct fire.

Rocket artillery

artillery rocketrocketsartillery rockets
Handguns and rifles, machine guns, anti-tank guns, tank main guns, many types of unguided rockets (although missiles, mortars, howitzers, rocket artillery, multiple rocket launchers, and artillery in general, cruise missiles, and ballistic missiles, etc., are indirect), and guns mounted in aircraft are examples of weapons primarily designed for direct fire.

Multiple rocket launcher

MLRSMultiple Launch Rocket Systemrocket launcher
Handguns and rifles, machine guns, anti-tank guns, tank main guns, many types of unguided rockets (although missiles, mortars, howitzers, rocket artillery, multiple rocket launchers, and artillery in general, cruise missiles, and ballistic missiles, etc., are indirect), and guns mounted in aircraft are examples of weapons primarily designed for direct fire.

Cruise missile

cruise missileshypersonic cruise missilecruise
Handguns and rifles, machine guns, anti-tank guns, tank main guns, many types of unguided rockets (although missiles, mortars, howitzers, rocket artillery, multiple rocket launchers, and artillery in general, cruise missiles, and ballistic missiles, etc., are indirect), and guns mounted in aircraft are examples of weapons primarily designed for direct fire.

Ballistic missile

ballistic missilesthrow-weightballistic
Handguns and rifles, machine guns, anti-tank guns, tank main guns, many types of unguided rockets (although missiles, mortars, howitzers, rocket artillery, multiple rocket launchers, and artillery in general, cruise missiles, and ballistic missiles, etc., are indirect), and guns mounted in aircraft are examples of weapons primarily designed for direct fire.

Close air support

air supportground supportCAS
Handguns and rifles, machine guns, anti-tank guns, tank main guns, many types of unguided rockets (although missiles, mortars, howitzers, rocket artillery, multiple rocket launchers, and artillery in general, cruise missiles, and ballistic missiles, etc., are indirect), and guns mounted in aircraft are examples of weapons primarily designed for direct fire.

Canon de 75 modèle 1897

75 mmFrench 7575mm guns
Indirect fire is most commonly associated with field artillery (although field artillery was originally and until after World War I a direct fire weapon, hence the bullet-shields fitted to the carriages of guns such as the famous M1897 75 mm) and mortars.