Broadly, there are two very different approaches to artillery observation. Either the observer has command authority and orders fire, including the type and amount of ammunition to be fired, to batteries. Or the observer requests fire from an artillery headquarters at some level, which decides if fire will be provided, by which batteries, and the type and amount of ammunition to be provided. The first is characterised by the British, the second by the United States. In World War II both Germany and the Soviet Union tended towards the British method.