A field gun is a field artillery piece. Originally the term referred to smaller guns that could accompany a field army on the march, that when in combat could be moved about the battlefield in response to changing circumstances, as opposed to guns installed in a fort, or to siege cannons and mortars which are too large to be moved quickly, and would be used only in a prolonged siege.
A WWI French 105 mm field gun
German field guns captured by the NZEF displayed in London, 1918
Field artillery is a category of mobile artillery used to support armies in the field. These weapons are specialized for mobility, tactical proficiency, short range, long range, and extremely long range target engagement.
French Napoleonic artillery battery. Photo taken during the 200th anniversary reenactment of the battle of Austerlitz in 1805.
U.S. Army troops in Europe, spring 1945, with artillery shells labeled as "Easter eggs for Hitler".
An illustration of a bronze "thousand ball thunder cannon" from the 14th-century Ming Dynasty book Huolongjing. The cannon is an early example of pre-modern mobile battlefield artillery.
Calling in and adjusting artillery fire on a target visible to a forward observer but not to the soldiers manning the guns, themselves
