Answer:
Explanation: World War 1 popularized the use of the machine gun, capable of bringing down row after row of soldiers from a distance on the battlefield. This weapon,along with barbed wire and mines, made movement across open land both difficult and dangerous. Thus trench warfare was born. They also developed air-cooled machine guns for airplanes and improved those used on the ground making them lighter and easier to move. They made war much shorter than earlier wars. They also made it easier for the allies to advance through Germany.
