Railroads increased the speed a nation could mobilize its army and move it to its frontier. Railroads also eased the problem of supplying a large army. Telegraphs and telephones greatly speeded up communications. Electric lights allowed factories to work around the clock, increasing the production of armaments. By World War One, the airplane had been invented and powered dirigibles had been perfected, greatly enhancing the role of aerial observation. The Bessemer process made steel a low cost commodity and this allowed improvements in firearms and artillery.