The 644th moved to its first base in France in September, and from Coulommiers Airfield struck defended villages, railroad bridges and overpasses, marshalling yards, military camps, and communications centers to support the Allied assault on the Siegfried Line through the middle of December. In December, the unit participated in the Battle of the Bulge by striking marshalling yards, railheads, bridges, and vehicles in the battle area through January 1945. The squadron's bombing of targets in the Ardennes, when it made many attacks on German lines of communications, from 23 to 25 December 1944, earned it a Distinguished Unit Citation. The squadron began training in January 1945 for night missions, while continuing its daylight operations. It replaced its A-20G and A-20H aircraft with nose-mounted guns with black A-20J and A-20Ks with navigator positions for night operations. These operations were aided by Martin B-26 Marauder flare ships to illuminate the area, and Douglas A-26 Invaders to mark targets with special bombs that burned with various colors. Successful night missions were flown in February, but the swift advances of Allied forces and need for daytime support resulted in a return to daylight operations. The 644th continued to fly ground support and air interdiction missions, aiding the Allied drive across the Rhine and into Germany from February through April 1945. The squadron converted to the Douglas A-26 Invader in 1945, but did not fly combat missions with its new bomber. After V-E Day, the squadron left Europe in June 1945 and reassembled at Seymour Johnson Field, North Carolina in August. It was inactivated at Myrtle Beach Army Air Field in November 1945. Missile training The squadron was redesignated the 644th Strategic Missile Squadron and activated at Vandenberg Air Force Base, California in January 1959 as a missile training squadron. The squadron was assigned to the 704th Strategic Missile Wing and was intended to train Royal Air Force personnel in the operation and launching of the SM-75 Thor Intermediate Range Ballistic Missile (IRBM). Anticipating the inactivation of the 704th Wing in July, the squadron was attached to the 1st Missile Division on 6 April 1969. However, although Thors were provided to NATO allies, no USAF units were equipped with them, when the Army's Jupiter missile was selected as the IRBM for US forces, and the squadron was inactivated on 15 December 1959 without being manned. Strategic bomber operations In the late 1950s, Strategic Air Command