The 15th was originally part of the 27th Bombardment Group (Light), assigned to Fifth Air Force in the Philippine Islands. However the group's planes (A-24s), did not arrive by 7 December 1941, and due to the deteriorating situation in the Philippines after the Japanese invasion, they were diverted to Australia. Surviving members of the group reformed into a combat unit in Australia and fought in the Dutch East Indies and New Guinea Campaigns. When the 27th Bombardment Group was inactivated and transferred back to the United States for re-equipping, the surviving members of the group were first transferred back to the United States, then to the UK in May where they received their Bostons from No. 226 Squadron RAF. The men and aircraft were organised and formed as the 15th Bomb Squadron, the 15th LBS having been a part of the 27th while in training during 1940/41 before being inactivated prior to the groups deployment to the Philippines. With the pilots having had extensive combat experience against the Japanese in the Pacific War, these airmen's mission was to train with their RAF counterparts in preparation for the upcoming Eighth Air Force strategic bombing campaign against the Germans. After a few weeks of familiarisation training with the new aircraft, on 4 July 1942, six American crews from the 15th Bomb Squadron joined with six RAF crews from RAF Swanton Morley for a low-level attack on Luftwaffe airfields in the Netherlands, becoming the first USAAF unit to bomb targets in Europe. The 4 July raid had been specifically ordered by General Henry H. "Hap" Arnold and approved by President Roosevelt. Arnold believed that 4 July would be an ideal day for the USAAF to open its strategic bombing campaign against the Nazis, but General Carl Spaatz did not have any of his heavy Eighth Air Force bomb groups ready for operational missions. Two of the 15th's planes did not return from the mission, along with one RAF aircraft. The squadron commander, Captain Charles Kegelman, plane was shot up badly and almost did not return. Spaatz considered the mission a "stunt" triggered by pressure in the American press who believed the people of both the United States and Great Britain needed a psychological boost. However, Kegleman was awarded the Distinguished Service Cross and its British equivalent for his valour on that Fourth of July mission, the first Eighth Air Force airman to receive the nation's second highest combat decoration. The 15th flew most of its missions from Molesworth in its Bostons, and did not receive USAAF Douglas A-20 Havoc aircraft until 5 September.