He led a squad when his unit moved forward in darkness to meet the threat of a breakthrough by elements of the 17th German Panzer Grenadier Division. Assigned to protect the left flank, he discovered hostile troops digging in. As he reported this information, several German machine guns opened fire, stopping the American advance. Knowing the position of the enemy, Sgt. MacGillivary volunteered to knock out one of the guns while another company closed in from the right to assault the remaining strongpoints. He circled from the left through woods and snow, carefully worked his way to the emplacement, and shot the two camouflaged gunners at a range of three feet as other enemy forces withdrew. Early in the afternoon of the same day, Sgt. MacGillivary was dispatched on reconnaissance and found that Company I was being opposed by about six machine guns reinforcing a company of fanatically fighting Germans. His unit began to attack but was pinned down by furious automatic and small-arms fire. With a clear idea of where the enemy guns were placed, he voluntarily embarked on a lone combat patrol. Skillfully taking advantage of all available cover, he stalked the enemy, reached a hostile machine gun, and blasted its crew with a grenade. He picked up a submachine gun from the battlefield and pressed on to within 10 yards of another machine gun, where the enemy crew discovered him and feverishly tried to swing their weapon into line to cut him down. He charged ahead, jumped into the midst of the Germans, and killed them with several bursts. Without hesitation, he moved on to still another machine gun, creeping, crawling, and rushing from tree to tree, until close enough to toss a grenade into the emplacement and close with its defenders. He dispatched this crew also, but was himself seriously wounded. Through his indomitable fighting spirit, great initiative, and utter disregard for personal safety in the face of powerful enemy resistance, Sgt. MacGillivary destroyed four hostile machine guns and immeasurably helped his company to continue on its mission with minimum casualties.