Two words: Japan. Germany.
Japan was the extreme case. While demonstrating that it is possible to effect change on a civilizational level, unconditional surrender and sustained occupation were necessary to accomplish the goal. Anything less leaves only short term change and, as Iraq showed, is a waste of the victor’s lives and treasure.
The neoconservative belief that we can change the culture of other nations, short of sustained domination, leads to overly long wars destined to be repeated. Afghanistan is the poster boy, Islam the paradigm. As Napoleon said, “If you’re going to take Vienna, take Vienna.”
In other words, half-assed warfare is a loser’s game. See also the Korean ‘conflict,’ and Viet Nam.