The Battle of Troina began on 31 July, when the Germans repelled an advance by the 39th Infantry, a 9th Infantry Division formation temporarily attached to the 1st Infantry Division, commanded by Major General Terry Allen. This setback forced Bradley and Allen to orchestrate a massive assault. Early on the first day of fighting, Sergeant Gerry H. Kisters of the 91st Cavalry was awarded the Medal of Honor for silencing two machine gun positions. Over the next six days the men of the 1st Infantry Division, together with elements of the 9th Division, a French Moroccan infantry battalion, 165 artillery pieces (divided among 9 battalions of 105-mm howitzers, 6 battalions of 155-mm howitzers, and 1 battalion of 155-mm "Long Tom" guns), and numerous Allied aircraft, were locked in combat with Troina's tenacious defenders. Control of key hilltop positions changed hands often, with the Germans and Italians launching more than two dozen counterattacks during the week-long battle. During one Italian counterattack, Lieutenant-Colonel Giuseppe Gianquinto's 1st Battalion, 5th Regiment of the 'Aosta' managed to take 40 American prisoners.