For conspicuous gallantry and intrepidity in action while serving as a Forward Observer with Company E, Second Battalion, Third Marines, First marine Division in connection with operations against the enemy in the Republic of Vietnam. From 28 May to 3 June 1968, during Operation Scotland II, Company E was heavily engaged with numerically superior North Vietnamese Army forces southeast of Khe Sanh Combat Base. Through out the battle, Captain Carlin continuously exposed himself to enemy small arms fire as he directed supporting fires against hostile positions. When his radio operator became a casualty during a mortar attack on the morning of 1 June, Captain Carlin quickly retrieved the radio and, although suffering a concussion himself, continued to call in accurate and timely fires, controlling as many as twelve missions simultaneously. When he was seriously wounded later the same day, he steadfastly refused medical aid and disregarded his own safety as he adjusted night defensive fires. The following morning, Captain Carlin unhesitatingly moved to a dangerously exposed area and directed highly effective counterbattery fires while a relief unit advanced to replace his company in the vital position. Although wounded for the third time, he ignored his weakened condition and remained in the hazardous area until he briefed his replacement concerning the tactical situation. His fortitude and bold fighting spirit inspired all who observed him and contributed immeasurably to the accomplishment of his unit's mission. By his courage, superb initiative and selfless devotion to duty at great personal risk, Captain Carlin upheld the highest traditions of the Marine Corps and the United States Naval Service.