Conditions were horrendous. The trenches were extremely narrow, often damp or wet (this led to infections known as trenchfoot), there was mud, bodies, and rats everywhere. Poor hygiene, little sanitation or protection from the elements. Constant danger from the enemy, and from going over the top into the area in between known as "No Man's Land". No Man's Land was littered with bodies, muddy, and lined with jagged barbed wire that was set up to funnel men right into machine gun fire, shells that had and hadn't exploded, the unexploded shells were a danger within themselves. The mud itself was a killer. It could and would suck men in like quicksand and they couldn't escape. When chlorine gas started to be used, it got worse because if a gas bomb made it into the trenches the men in there were often-times trapped with it. Initially tanks were useless, they were slow, and got stuck in the mud entirely too easy, but the French and British invented a better one, that was more agile and easier to navigate through No Man's Land. The German's didn't really manufacture tanks in the First World War because their initial failure made the Germans view them as obsolete. It was a tedious form of warfare that resulted in little area gained because one side was always outpacing the other. That's why in WWII all parties involved were willing to avoid trench warfare at all costs, and with advancements in technology the war went into the air, and there were greater battles at sea.