text: Offense
  into the enveloping force and the fixing force. (See figure 6-1.) The commander also allocates forces to
  conduct reconnaissance, security, reserve,and sustaining operations. The enveloping force, conducting the
  decisive operation,attacks an assailable enemy flank and avoids the enemy’s main strength en route to the
  objective. The fixing force conducts a frontal assaultas a shaping operation to fix the enemy in its current
  positions to prevent its escape and reduce its capability to react against the enveloping force. (SeeFM3-90-1
  for additional information.)
  Figure 6-1. Single envelopment
  DOUBLE ENVELOPMENT
  6-96. Double envelopmentresults from simultaneous maneuvering around both flanks of a designated enemy
  force (FM 3-90-1). A commander executing a double envelopment organizes friendly forces into two
  enveloping forces and one fixing force in addition to allocating reconnaissance, security, reserve, and
  sustaining forces. (See figure 6-2on page 6-20.) The commander typically designates the more important of
  the two enveloping forces as the main effort for resources. The enveloping force is the commander’s decisive
  operation if its action accomplishes the mission. Maneuver control graphics,and appropriate fire coordination
  measures, such as a restrictive fire line or boundary between converging forces and communications are
  essential to mission accomplishment and preventing fratricide during this envelopment. (SeeFM 3-90-1 for
  additional information.)