During World War I, the pistol was originally given to all military officers, whereas the rifle was reserved for regular soldiers. But, later on it was also given to tank drivers and pilots because they could not use the long rifles in cramped quarters, inside the tanks and airplanes.
The rifle was the standard weapon of the First World War. Compared to other weapons of the war, it was the easiest to produce in larger numbers and also easier for soldiers to carry in battle.
A bayonet is a knife, designed to fit on a rifle, effectively turning the gun into a spear.
Hand grenades were sticks with a fuse which when thrown by soldiers, would explode on impact. There were also timed grenades.
The machine gun, could fire 400-600 rounds per minute. The reality however was that these early machine guns would rapidly overheat and become inoperative without the aid of cooling mechanisms; they were consequently fired in short rather than sustained bursts.
The flamethrower, had the basic idea of spreading fire by launching burning fuel.
Considered uncivilized prior to World War One, the development and use of poison gas was necessitated by the requirement of wartime armies to find new ways of overcoming the stalemate of unexpected trench warfare.
The first tanks were produced by the British during WWI. The tank became the weapon that ended the stalemate in trench warfare. It could travel over barbed wire and also provided cover against enemy fire. However, the first tanks were too slow, would break down easily, and sometimes would get stuck in ditches or trenches.
Planes were also used for the first time. At first they were used to deliver bombs and for spying work but became fighter aircraft armed with machine guns, bombs and some times cannons. Fights between two planes in the sky became known as 'dogfights'.