Military reserve

A military reserve is a group of personnel or units held back by a commander. These troops are not committed to a battle right away. Instead, they remain available to address unforeseen situations. They also exist to exploit sudden opportunities that might appear during a fight. Commanders use reserves as a hedge against uncertainty. This means the size of the reserve depends on how much the commander knows about enemy intentions. If the situation is very uncertain, the reserve may be larger.

There are several specific ways a commander can use these forces. One method is to hold them back to defend against an attack from other enemy forces. Another method is to commit them to an existing battle if the enemy shows a vulnerability. They can also serve as relief for troops that are already fighting. This allows the active units to rest and regroup away from the front line. In the United States Army, doctrine suggests a specific process for this. A commander should reform another reserve after they commit their existing reserve.

Reserves function at many different levels of military organization. A small unit, such as a platoon, can be held back from a company-level engagement. On a much larger scale, an entire army corps can be kept in reserve. These large corps might consist of armored and mechanized divisions. Such units are used to exploit a breakthrough or to contain an enemy advance. It is important to understand how these levels interact. A group that is a reserve for one headquarters might not be a reserve for another. For example, a company held in reserve is a reserve for its battalion. However, it is not a reserve for the brigade or the division. This is because it is already committed to its parent battalion's sector.

Military experts categorize reserves into three distinct types. These categories are tactical reserves, operational reserves, and strategic reserves. While the source does not define the specific mechanics of each, they represent different scales of planning.

It is helpful to distinguish between a military reserve and a military reserve force. A military reserve refers to specific, trained, pre-organized forces. These forces operate on an on-call basis from the main military force. In contrast, a military reserve force is a larger organization. It is composed of individuals known as reservists. These reservists maintain their military skills through a long-term, part-time commitment. Their goal is to support their country if it is needed.

History provides notable examples of how these units have been used in major conflicts. During the First World War, the British Expeditionary Force used the British Reserve Army. This was a field army intended for a specific purpose. It was meant to carry out the breakthrough phase of the Somme offensive. This task was to occur once General Sir Henry Rawlinson's Fourth Army captured the German front-line trenches.

Another significant example occurred during World War II. The Soviet Red Army utilized the Reserve of the Supreme High Command. This was the principal reserve for the Soviet forces during the war. Today, this specific organization is part of the Russian Armed Forces. These historical examples show how reserves are vital for managing large-scale military movements.