The war of 1914-1918 relied on engineering. Without engineers there would have been no supply to the armies, because the RE's maintained the railways, roads, water supply, bridges and transport. RE's also operated the railways and inland waterways. There would have been no communications, because the RE's maintained the telephones, wireless and other signalling equipment. There would have been little cover for the infantry and no positions for the artillery, because the RE's designed and built the front-line fortifications. It fell to the technically skilled RE's to develop responses to chemical and underground warfare. And finally, without the RE's the infantry and artillery would have soon been powerless, as they maintained the guns and other weapons. Little wonder that the Royal Engineers grew into a large and complex organisation.