Editing Howitzer (section)

=== 20th century ===
In the early 20th century, the introduction of howitzers that were significantly larger than the heavy siege howitzers of the day made necessary the creation of a fourth category, that of "super-heavy siege howitzers". Weapons of this category include the famous [[Big Bertha (Howitzer)|Big Bertha]] of the German Army and the [[BL 15 inch Howitzer|15-inch (381&nbsp;mm) howitzer]] of the British [[Royal Marines|Royal Marine Artillery]]. These large howitzers were transported mechanically rather than by teams of horses. They were transported as several loads and had to be assembled at their firing position.<ref>Romanych, Marc; Rupp, Martin (2013). ''42 cm "Big Bertha" and German Siege Artillery of World War I''. Illustrated by Henry Morshead. Osprey Publishing. {{ISBN|978-1-78096-017-3}}</ref>

Field howitzers introduced at the end of the 19th century could fire shells with high trajectories giving a steep angle of descent and, as a result, could strike targets that were protected by intervening obstacles. They could also fire shells that were about twice as large as shells fired by guns of the same size. Thus, while a {{convert|75|mm|abbr=on}} field gun that weighed one ton or so was limited to shells that weigh around {{convert|8|kg|abbr=on}}, a {{convert|105|mm|abbr=on}} howitzer of the same weight could fire {{convert|15|kg|abbr=on}} shells. This is a matter of fundamental mechanics affecting the stability and hence the weight of the carriage.

As heavy field howitzers and light siege howitzers of the late 19th and early 20th centuries used ammunition of the same size and type, there was a marked tendency for the two types to merge. At first, this was largely a matter of the same basic weapon being employed on two different mountings. Later, as on-carriage recoil-absorbing systems eliminated many of the advantages that siege platforms had enjoyed over field carriages, the same combination of barrel assembly, recoil mechanism and carriage was used in both roles.{{Citation needed|date=May 2009}}

By the early 20th century, the differences between guns and howitzers were relative, not absolute, and generally recognized<ref>H. A. Bethell, ''Modern Guns and Gunnery'', (Woolwich: F. J. Cattermole, 1905, 1907, 1910)</ref> as follows:
* Guns – higher velocity and longer range, single charge propellant, maximum elevation generally less than 45 degrees.
* Howitzers – lower velocity and shorter range, multi-charge propellant, maximum elevation typically more than 45 degrees.

The onset of [[trench warfare]] after the first few months of [[World War I]] greatly increased the demand for howitzers that gave a steep angle of descent, which were better suited than guns to the task of striking targets in a vertical plane (such as trenches), with large amounts of explosive and considerably less barrel wear. The German army was well equipped with howitzers, having far more at the beginning of the war than France.<ref>{{cite book|first=Bruce I.|last=Gudmundsson|title=On Artillery|publisher=[[Greenwood Publishing Group]]|isbn=978-0-275-94047-8|year=1993}}</ref>

Many howitzers introduced in the course of World War I had longer barrels than pre-war howitzers. The standard German light field howitzer at the start of the war (the [[10.5 cm Feldhaubitze 98/09|10.5&nbsp;cm leichte Feldhaubitze 98/09]]) had a barrel that was 16 [[Caliber (artillery)|calibers]] long, but the light field howitzer adopted by the German Army in 1916 ([[10.5 cm leFH 16|105&nbsp;mm leichte Feldhaubitze 16]]) had a barrel that was 22 calibers long. At the same time, new models of field gun introduced during that conflict, such as the {{convert|77|mm|abbr=on}} field gun adopted by the German Army in 1916 ([[7.7 cm FK 16|7.7 cm Feldkanone 16]]) were often provided with carriages that allowed firing at comparatively high angles, and adjustable propellant cartridges.<ref>Hans Linnenkohl, {{lang|de|Vom Einzelschuss zur Feuerwalze}} (Koblenz: Bernard und Graefe, 1990), pp. 86 and 219–220</ref>

In the years after World War I, the tendency of guns and howitzers to acquire each other's characteristics led to the renaissance of the concept of the [[gun-howitzer]]. This was a product of technical advances such as the French invention of [[autofrettage]] just before World War I, which led to stronger and lighter barrels, the use of cut-off gear to control recoil length depending on firing elevation angle, and the invention of [[muzzle brake]]s to reduce [[recoil]] forces. Like the gun-howitzers of the 19th century, those of the 20th century replaced both guns and howitzers. Thus, the [[Ordnance QF 25 pounder|25-pounder "gun-howitzer"]] of the British Army replaced both the [[Ordnance QF 18 pounder|18-pounder]] field gun and the [[QF 4.5 inch Howitzer|4.5-inch howitzer]].<ref>[[25 pounder#Design]]</ref>

During [[World War II]], the military doctrine of [[Soviet deep battle]] called for extensive use of heavy artillery to hold the formal line of front. Soviet doctrine was remarkably different from the German doctrine of [[Blitzkrieg]] and called for a far more extensive use of artillery. As a result, howitzers saw most of the action on the [[Eastern Front (World War II)|Eastern front]]. Most of the howitzers produced by the [[USSR]] at the time were not self-propelled. Notable examples of Soviet howitzers include the [[152 mm howitzer M1938 (M-10)|M-10]], [[122 mm howitzer M1938 (M-30)|M-30]] and [[152 mm howitzer M1943 (D-1)|D-1]].

Since World War II, most of the artillery pieces adopted by armies for attacking targets on land have combined the traditional characteristics of guns and howitzers&nbsp;– high muzzle velocity, long barrels, long range, multiple charges and maximum elevation angles greater than 45 degrees. The term "gun-howitzer" is sometimes used for these (e.g., in Russia); many nations use "howitzer", while the UK (and most members of [[The Commonwealth of Nations]]) calls them "guns", for example [[L118 Light Gun|Gun, 105&nbsp;mm, Field, L118]].