Military reserve

Units, personnel, and resources not initially committed to battle and available to a commander

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. 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 represent a "hedge against uncertainty", the size of the reserve depends on the level of uncertainty a commander has about the enemy's intentions. Some of the different categories of military reserves are: tactical reserve, operational reserve, and strategic reserve.

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