That's not the way I heard it. The abbey was unoccupied by the Germans, until the U.S. made a huge blunder and bombed it into ruins. The Germans then occupied the ruins, which made perfect defensive positions and greatly increased allied casualties.
And that for some reason the US had no problem bombing the crap out of this huge church, and that some people saw this as really nasty.
PLEASE DO NOT PILE ON, I LOVE THE USA.