Which of the following is NOT a variety of envelopment?

The concept of envelopment in military strategy refers to maneuvering forces around the enemy's position to cut off support and create opportunities for destruction or surrender. The types commonly identified include single envelopment, double envelopment, and encirclement.

A single envelopment occurs when one flank of the enemy is attacked, while a double envelopment involves attacks on both flanks, surrounding the enemy more completely. Encirclement involves surrounding the enemy on all sides, effectively cutting them off entirely from any retreat or support.

In contrast, a direct strike does not fit within these types of envelopment as it generally refers to an assault straight at the enemy’s positions rather than maneuvering around them. This tactic focuses on straightforward engagement rather than the strategic encirclement or flanking that defines the various forms of envelopment.