"This monograph examines US Army doctrine concerning field fortifications in the rear area, and determines whether this doctrine is appropriate based upon the rear area requirements of the Army's keystone doctrinal manual, FM 100-5, Operations. The 1993 version of FM 100-5 provides for a force projection Army in place of the forward deployed Army of the Cold War. In the forward deployed Army, allies provided rear area security assistance, and rear areas were on friendly territory. In force projection operations, however, US forces may receive little rear are assistance, and rear areas may be on neutral or hostile territory. One response to these increased challenges is to fortify the rear area."
Defense Technical Information Center (DTIC): http://www.dtic.mil/dtic/