Encirclement

Lastly, since the force cannot retreat, unless it is relieved or can break out, it must fight to the death or surrender.

In that case, the encircled forces are enveloped in a fortified position in which long-lasting supplies and strong defences are in place, allowing them to withstand attacks.

Sun Tzu and other military thinkers suggest that an army should be not completely encircled but instead given some room for escape.

During the Winter War, Finland used "pocket tactics" against the Soviet Union, called motti; in the context of war, motti describes a tactic that the Finns used to immobilise, segment, surround and destroy the Soviet troops that were many times as large as them.

Because of the extreme difficulty of this operation, it cannot be executed unless the offensive force has a vast superiority, either in technology, organization, or sheer numbers.

Diagram of the encirclement of ISIS forces in the Second Battle of Tikrit (2015). The blue arrows indicate allied attacks, while the red line is the line of encirclement as of 9 March 2015.
Encirclement of Stalingrad
An encirclement during the Japanese invasions of Korea (1592–1598)