Main bodies of parachute troops will be instructed to attack their objectives (an airdrome, town, or military position) as a coordinated unit or force. Tactics, of course, may be expected to vary, depending upon the objective. Before an attack of any importance is launched, companies will get into contact with battalions, and battalions with regiments. Companies may descend some distance apart (say half a mile to a mile and a half), but they will try so to land that they can operate as a normal infantry unit. To produce the requisite coordination, radio communication will be essential from the moment the descent is complete. The dropping zone of one main attacking body may be as much as 24 square miles; in Crete the density at which parachute troops were dropped on the first day was from 400 to 500 (about 1 battalion) per square mile.