St. Mihiel Offensive During the summer months, while America's seven combat squadrons were fighting over the Marne, the Air Service continued its build-up on the Toul Front and by Sept. 12, 1918, when the St. Mihiel Offensive began, 20 additional squadrons -- seven pursuit, nine day-observation, three day-bombardment and one night observation -- had been formed. In addition, two pursuit units -- the 17th and 148th -- had gone into action in July on the British Front near Dunkerque on the English Channel. Though all its pilots and ground personnel were members of the U.S. Air Service, their equipment (Sopwith Camel airplanes, trucks, tents and even typewriters) was British. These two units remained attached to the British for operational use until shortly before the Armistice. They not only engaged the enemy in the air, but were frequently used to bomb and strafe ground targets. Gen. Billy Mitchell readied an enormous armada of 1,481 airplanes for the St. Mihiel Offensive. He had under his direct command 26 U.S., 61 French and three Italian squadrons; there were also nine British squadrons available for additional assistance. When this force was unleashed on the enemy on Sept. 12, 1918, the wisdom of his tactics was immediately evident. He used one-third of his force for direct support of front-line ground troops and the rest for bombing and strafing of enemy targets in rear areas. The Germans retreated to prevent being surrounded, and within one week the St. Mihiel salient was regained by the Allies for the first time since 1914. Click here to return to the Air Service Overview. Find Out More Related Fact Sheets Sopwith Camel F.1 Note: The appearance of hyperlinks does not constitute endorsement by the National Museum of the USAF, the U.S. Air Force, or the Department of Defense, of the external website, or the information, products or services contained therein.