There are two types of delay. Delay in sector requires a unit to slow and defeat as much of the enemy force as possible without sacrificing tactical integrity. Delay forward of a specified line for a specified time or event entails greater risk. The unit must prevent the enemy from reaching a specified line for a specified time or event, regardless of cost. The concept of operations must clearly identify any restrictions.
Deception is important.
The delaying force must keep the enemy in doubt as long as possible concerning the location of the successive delaying positions. A withdrawal is a planned operation in which a force in contact disengages from an enemy force. To conserve resources for future operations. To gain time. To avoid combat under unfavorable conditions.