text: Chapter 7
  were approximately 10,000 while the confederate forces suffered approximately 5,000
  casualties.
  Vincent Esposito
  Figure 7-4. Historical example, defense of a linear obstacle, Fredericksburg, 1862
  PERIMETER DEFENSE
  7-89. The BCT and its subordinate units often use a perimeter defense when conducting airborne and air
  assault operations, as well as when conducting operations in noncontiguous areas of operations. The BCT
  presents no assailable flanks to the enemy and allows the defender to reinforce a threatened area rapidly.
  Some disadvantages of a perimeter defense include its isolation and the vulnerability of its concentrated units
  to enemy fires.
  7-90. Acommander establishes a perimeter defense when the unit must hold criticalterrain,such as a strong
  point,or when it must defend itself in areas where the defense is not tied in with adjacent units. Depending
  on the situation, the commander maximizes the use of class IV barrier material, utilize engineer assets to
  create vehicle and crew served fighting positions, and manpower to emplace obstacles of many types