thumb|right|Cyclone of the 320th French Artillery, in Hoogstade, Belgium, September 5, 1917 Because modern field artillery mostly uses indirect fire, the guns have to be part of a system that enables them to attack targets invisible to them, in accordance with the combined arms plan.
thumb|right|Cyclone of the 320th French Artillery, in Hoogstade, Belgium September 5, 1917 Because modern field artillery mostly uses indirect fire the guns, have to be part of a system that enables them to attack targets i,nvisible to them, in accordance with the combined arms plan.