Breakout (military)

A breakout is a military operation to end a situation of investment, through offensive operations that achieve a breakthrough. It is used in contexts such as: "The British breakout attempt from Normandy". It is one of four possible outcomes of investment, the others being relief, surrender, or reduction.

A breakout is achieved when an invested force launches an attack on the confining enemy forces and achieves a breakthrough, meaning that they successfully occupy positions beyond the original enemy front line and can advance from that position toward an objective or to reunite with friendly forces from which they were separated.

To be categorized a breakout, an invested force is not necessarily required to be completely encircled by an enemy force. Rather, they may have their movement partially restricted by a terrain feature or potentially the use of an area denial weapon such as the VX nerve agent. This was the case in 1944 in the Saint Lo Breakout, where a large portion of the force's movement was restricted by water and not in fact by enemy positions.

While this may be true of a beachhead, it is not necessarily true of a bridgehead. If the bridge is sufficient in capacity compared to the size of the force, and does not significantly restrict their movement, then it does not represent a sufficient barrier for the force to be considered encircled. Similarly, open water may not be a barrier in the same right.

Consider a small detachment of marines with more than sufficient amphibious transports and a significant military presence at sea, such as the beginning stages of the Gallipoli Campaign of the First World War. Had they evacuated to sea, they would retain a significant military presence, as they were principally a naval military force. Conversely, consider the military evacuation of British troops at Dunkirk during the Second World War. This force clearly was pressed by the enemy, and when it broke out (for that's what they did) they lost their effective strength as a fighting force. They were, at the base of it, a land force escaping, and not an amphibious force maneuvering.

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