the consequences of the crusades are still with us, eg George W Bush calling for a crusade, which convinced much of the Muslim world that America wanted to wipe Islamic countries out. I still don't know if he just spoke clumsily, as he often did, or if he really meant it and they were right.
The first crusade was the only militarily successful one (though the sixth achieved a great deal by treaty). Gradually, Europeans just lost interest as subsequent crusades failed.