Combat tactics at the start of the "Great War" were based on experiences from the colonial wars of the late-19th century. Advancing rows of massed infantry using volley rifle fire, followed by bayonet charges, combined with supporting cavalry and mobile field artillery. This was the battle-tested recipe for land warfare.

With the invention of the machine gun and quick-firing artillery, along with direct aerial observation by aircraft, all that changed. Massing large numbers of infantry in the open hoping to surprise and out-maneuver your opponent became a fruitless endeavor. Tactics tried and true for hundreds of years became suicidal. Armies, suffering massive casualties, were forced to abandoned those traditional ways. Opposing forces were forced into fixed lines of defense with no practical means to press an effective attack. Trench Warfare became the face of battle which required a new class of related weaponry.

After centuries of being little more than a military curiosity, the hand grenade became main-stream. Grenade throwers, dischargers and the infantry mortar came into existence. Opposing armies began desperately experimenting to gain an advantage. Rudimentary designs were rushed into mass-production and it's no surprise many of these concepts left a lot to be desired as practical weapons. Also, it became clear, manufacturing simplicity was critical if production requirements were to be met.

Weapon design rapidly evolved into a wide variety of shapes, sizes and functionality. Many ideas were tried, but developing those into practical and effective weapons proved to be an elusive goal. Glaring flaws became apparent once the confines of development labs and proving grounds were exchanged for the muddy expanses of  "No Man's Land".
Trial-by-Fire was the process by which success was achieved.