Why did both sides in world war 1 turn to new weapons?

to combat the deadlock in the trenches, like for example the tank, it was made to break through trench lines, and the machine gun it was made to mow down assaults on trenches, or positions. Gas attacks were also used to help in offensives, for it rendered the enemy trenches paralyzed, meaning they cant fight back, because they are dying

Explanation:

on april 6, 1917, the u.s. joined its allies--britain, france, and russia--to fight in world war i. under the command of major general john j. pershing, more than 2 million u.s. soldiers fought on battlefields in france.