Military reserve

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A military reserve, active reserve, reserve formation, or simply reserve, is a group of military personnel or units that is initially not committed to a battle by its commander, so that it remains available to address unforeseen situations or exploit sudden opportunities.^[1] Reserves may be held back to defend against attack from other enemy forces, to be committed to the existing battle if the enemy exposes a vulnerability, or to serve as relief for troops already fighting. As reserves (especially in the defence) represent a "hedge against uncertainty", the size of the reserve depends on the level of uncertainty a commander has about the enemy's intentions.^[2] Some of the different categories of military reserves are: tactical reserve, operational reserve, and strategic reserve.

A military reserve is different from a military reserve force, which is a military organization composed of military personnel (reservists) who maintain their military skills and readiness in a long-term part-time commitment to support their country if needed. Military reserve refers to specific trained pre-organized forces operating on an on-call basis from the main military force.^[3]