White peace refers to when one or more alliances involved in an inter-alliance war agree to peace with one another without imposing any terms on one another.
However, in Politics and War this term is commonly used when an alliance doesn't admit defeat thereby it doesn't "surrender" since there is no admission of defeat. Despite there being no admission of defeat in a White Peace, a "no re-entry" clause is usually imposed upon the alliance receiving the White Peace; where they cannot rejoin the war they are leaving.