A key tactical innovation during World War I that significantly changed warfare was the widespread use of trench warfare. This method involved digging extensive networks of trenches along the Western Front, which became a defining characteristic of the war. Soldiers lived and fought in these trenches, leading to brutal conditions, stalemates, and high casualties. This strategy necessitated new forms of warfare, including the use of machine guns, poison gas, and artillery bombardments. The static nature of trench warfare also prompted the development of tanks and air combat strategies, fundamentally altering military tactics and the battlefield experience in the modern era.