 Their most notable success came on 7 January, when PAVN gunners shot down a helicopter carrying the commander of the 2/12th Cavalry, Lt. Col. Robert L. Gregory, killing him and 6 others on board.After a week of hard fighting, however, the 2nd Division was reaching the limit of its endurance.The final clash of the campaign came on 10 January when the 2/12th Cavalry, tangled with a reinforced PAVN battalion near LZ Ross.