A tank is a large type of Armoured vehicle with tracks, designed for front line combat. Tanks have a mounted rotating gun turret. They combine this with heavy vehicle armor providing protection for the crew of the weapon and operator. This helped clear the way for soldiers and other vehicles.
Poison gas was indiscriminate and could be used on the trenches even when no attack was going on. These attack meant soldiers would have to put on gas masks, and if these were unsuccessful, the attack could leave a victim in pain for days even up to weeks before he finally dies from his injuries.
Submarines are underwater ships that can go fully underwater and come anove ghe water surface. These are used for so that they know they are safe underwater and can travel without being seen.
A machine gun is designed to fire at a rate of three to eighteen hundred rounds per minute. This changed how quickly a group of soldiers can be killed.