The military use of railways derives from their ability to move troops or material rapidly and, less commonly, on their use as a platform for military systems (like armoured trains and heavy artillery). Until recently, the mobility of large armies generally depended on control of railways to move reinforcements, ammunition and food, as the locomotive and railways cars proved far superior to animal-drawn equipment. Historians Augustus J. Veenendaal and H. Roger Grant capture the critical impact of railways in an abundance of conflicts worldwide, from the German revolutions in the 1840s to the Gulf War in the 1990s.