Final answer:
Machine guns in WWI offered increased firepower but led to mass casualties. The defensive nature of the war made offensive charges against machine guns less effective.
Step-by-step explanation:
The use of machine guns in World War I had both benefits and limitations. One benefit was the increased firepower they provided, allowing a single soldier to fire hundreds of rounds per minute and drastically change the dynamics of an infantry attack. However, this also led to horrific injuries and mass casualties on the battlefield, as soldiers running across open fields became easy targets. Additionally, the defensive nature of the war forced military commanders to reconsider the effectiveness of offensive charges against enemies armed with machine guns.