During the years 1933–1937, Oliver served as a District Engineer in Vicksburg, Mississippi, and in 1938, he attended the U.S. Army War College in Carlisle, Pennsylvania.[5] After his War College studies, Oliver was assigned as an instructor to the U.S. Army Command and General Staff School at Fort Leavenworth, Kansas. He served in this capacity until 1940, when he was assigned as the Armored Force Engineer at Fort Knox, Kentucky. While there, Oliver, now promoted to colonel, initiated the research that led to the development of the steel treadway bridge.
In September, Oliver went to London, England to assist in the planning for Operation Torch (Allied invasion of North Africa). Oliver was promoted to the two-star rank of major general on November 20, 1942,[2] then CCB under his command landed successfully near the city of Oran on November 8, 1942, and started to advance toward the Tafaraoui airfield, occupying it with little resistance that same day. He was awarded the Army Distinguished Service Medal.[6] CCB encountered its first major enemy resistance at Medjez-el-bab, Tunisia where they fought for fours days starting on December 6, 1942.
Oliver returned to the United States and was appointed commander of the 5th Armored Division, where he succeeded Brigadier General Sereno E. Brett at Camp Cooke in early 1943. Oliver led the division throughout the remainder of the war, including training in the Mojave Desert near Needles, California, through March 1943, the Tennessee Maneuvers through the Summer, and final validation and reorganization of the division at Pine Camp (Now Fort Drum, New York) through the winter into early 1944.
Oliver led the division on two ships to England, arriving on February 24, 1944, in preparation for the Allied invasion of Normandy. The division served on the Western Front starting with landing on Utah Beach on July 26, 1944, until Victory in Europe Day on May 8, 1945, and after. The 5th Armored Division, under Major General Oliver's command, was the first division to reach the Seine River, the first division to reach Luxembourg, the first division to fight in Germany, and when halted by orders from the U.S. Ninth Army, the division sat 45 miles from Berlin, closer than any other American division.[7]
A street in Luxembourg City is named in honour of Major General Lunsford E. Oliver.[8]