Why amphibious raiders train to disengage as well as attack

Why are Royal Marines and United States Marines so difficult to eliminate even when facing unusual threats?

Their raiding mission requires practiced withdrawal from superior forces, so survival, disengagement, and adaptation are trained skills rather than improvised reactions.

A raid succeeds only if the force can reach the objective, act, and then break contact before a larger enemy closes around it. Amphibious troops therefore rehearse disengagement and withdrawal more often than many formations whose doctrine assumes a continuous front. Survivors carry lessons into the next operation, making the unit more dangerous over time. The panel also points to strong academic and professional performance among Marines as evidence that physical aggression and careful operational thought are complementary rather than opposed.