After VII Corps took the port city of Cherbourg, VIII Corps began moving south against German forces in the middle of the Cotentin Peninsula. The Germans had the high ground, and the fighting was further complicated by the bocage countryside—a series of farmers fields and pastures forming a latticework, with each unit separated by walls of earth up to six feet high supporting dense shrubbery and trees. The German defenders had every advantage over the Americans, whose tanks would tip up and expose their thin bottom armor as they attempted to cross the barriers. By mid July, field expedient devices were developed to equip tanks to penetrate the hedgerows and restore battlefield mobility. Such specially equipped tanks were referred to as Rhino Tank.