No, the Crusade was a huge success. It achieved its goals without having so much as a battle.
Because eventually something bad came of it doesn't mean it was a failure. You can win a battle and lose a war; you don't say that a won battle was actually lost because the casualties sustained in it lead to you losing a battle two months later.
Vellos, I believe that what you described is called a Pyrrhic victory. Its a victory, technically, but the cost outweighed the benefits.
