Being an artillery forward observer or part of an observation team was one of the most dangerous positions on the battlefield in World War II. These highly skilled personnel traveled with an infantry squad or set up an observation post in order to call in fire missions. Their loss rates were on par with rifle company losses in the ETO. A fire mission was coordinated between several entities: forward observers, fire direction centers (usually at Battalion), and the battery firing personnel. In the last year of the war, many FOs flew in L-4 observation aircraft which proved to be invaluable in bringing down immense fire on the enemy. The British and Canadian armies had similar systems throughout the war.