All wars are fought under constraints. Wars for limited aims generally suffer from more numerous and intent constraints because the value of the political objective sought tends to be lower, and thus states will often do less and pay less for a shorter time. The most important constraints are the value of the enemy’s political objective, time, internal public opinion, the international political environment (which usually means third-party nations with an interest in your war), geography, and the military means (which includes nuclear weapons). Military and political leaders need to understand how these constraints affect their ability to fight and win the war, and they must also determine whether the constraints are actual or self-imposed, and, if they are self-imposed, whether or not they are wise. The constraints are examined via examples from the Korean, Vietnam, and Iraq Wars.