What was the main military strategy used on the western font

Trench warfare in World War I meant that the armies dug into trenches to hold their ground.  But it proved impossible for them to make any advances against each other.   If they would try to mount an attack, venturing into "no man's land" between the trenches, they'd get mowed down by machine gun fire.   In addition to bullets and artillery fire, trench warfare also came to involve the use of chemical weapons like mustard gas.  Trench warfare in World War I was miserable and gruesome.  

the right answer is the end of world war ii

after the end of a global wwii all the nations involved, in an attempt to create an organization to maintain world peace. this agreement would work settling international disputes via negotiation and arbitration instead of leading the issues escalate to another war.