There were no four-leaf clovers mounted to the turrets, but an Irish Defense Forces crew still managed to pull off one of the biggest upsets at the U.S. Army’s premier armor competition this month. The Irish soldiers beat American crews to claim first place in the Bradley Fighting Vehicle division at the Sullivan Cup, despite the Irish Army not operating any Bradleys of its own.The Sullivan Cup, hosted at Fort Benning, Georgia, is a weeklong eve…