An unconditional surrender is a surrender in which no guarantees, reassurances, or promises are given to the surrendering party. It is often demanded with the threat of complete destruction, extermination or annihilation.

Surrender, in military terms, is the relinquishment of control over territory, combatants, fortifications, ships or armament to another power. A surrender may be accomplished peacefully or it may be the result of defeat in battle. A sovereign state may surrender following defeat in a war, usually by signing a peace treaty or capitulation agreement. A battlefield surrender, either by individuals or when ordered by officers, normally results in those surrendering becoming prisoners of war.