For the soldiers from the First World War barbed wire was a crucial defensive weapon. Both sides used barbed wire to slow enemy soldiers from approaching. The military use of barbed wire was quickly adapted, by making the barbs longer and sharper. Millions of kilometers of barbed wire were laid by both sides. The only time it was safe to lay the wire was at night. Barbed-wire was usually placed far enough from the trenches to prevent the enemy from approaching close enough to lob grenades in. Sometimes barbed-wire entanglements were set up in order to channel attacking infantry into machine-gun fire.
The first large-scale use of lethal poison gas on the battlefield was by the Germans on April 22, 1915 during the Battle of Second Ypres. Poison gas was probably the most feared of all weapons in World War One. Poison gas could be used on the trenches. A poison gas attack meant soldiers had to put on crude gas masks and if these were unsuccessful, an attack could leave a victim in agony for days and weeks before he finally succumbed to his injuries.
Flamethrowers brought terror to the allied soldiers when used by the German army in the early phases of the First World War in 1914 and 1915. The basic idea of a flamethrower is to spread fire by launching burning fuel. Using pressurized air and carbon dioxide or nitrogen it belched out a stream of burning oil for as much as 18 metres. Part of the effectiveness of the flamethrower was in the terror it created, causing panic in enemy lines which could then be exploited. Flamethrowers were a very useful weapon when used at a short-range, but they came with some crucial drawbacks. The men who operated these machines had short life expectancy.
In the First World War all infantrymen were provided with bayonets. A bayonet is a knife or dagger fitted to the muzzle of the rifle barrel, effectively turning the gun into a spear. The bayonet was the infantryman's primary close combat weapon in trench warfare. The bayonet was more of a defensive weapon because of the increasing use of machine guns against an advancing army.
In attempting to fight through enemy trenches, or to defend against attack, all armies came to rely heavily on grenades. The first grenades in 1914 were often hand-made, consisting of old cans filled with nails and bits of metal and packed with gunpowder. They were risky because of premature explosions. By the end of 1915, all armies were being supplied with hand bombs. The British and Canadians used egg-shaped hand grenades, which could be thrown about 30 metres. By 1917, all infantry carried grenades.
The First World War tank developed from the interest of some military officers as a means of crossing trench obstacles and breaking through barbed wire. British forces first used tanks during the Battle of the Somme in September 1916. They were effective in crossing trenches and wire entanglements, but they failed to break through the German lines. The tanks’ real problems were slow speed, mechanical failures, and inability to cross soft or heavily cratered ground.
The machine gun, personified the battlefields of World War One. Machine guns of all armies were large, heavy and ill-suited to portability for use by rapidly advancing infantry troops. Each weighed somewhere in the 30kg-60kg range - often without their mountings, carriages and supplies. Germans quickly grasped the potential importance of machine guns on the battlefield. As the war developed machine guns were adapted for use on tanks on broken ground, particularly on the Western Front .