The initial bombing aircraft were extremely defenseless on the ground and could only carry little bombs. Long-range bombers were developed toward the end of the war that were both faster and could carry more bombs. More and more enemy planes took to the air, and soon air battles broke out between the pilots.

At the Battle of the Somme in September 1916, British forces first utilized tanks. While they were successful in navigating over trenches and through wire mazes, they were unable to penetrate the German lines.

An estimated 85,000 of the 91,000 gas deaths during World War I were caused by phosgene or diphosgene (trichloromethane chloroformate). During World War I, "mustard gas" [bis(2-chloroethyl) sulfide] was the most widely deployed gas.