From Joe Baugher's great website that Bill posted.
The USAAF took delivery of its first B-24As in June of 1941. Only nine of these B-24As were actually delivered to the USAAF, all between June 16 and July 10, 1941. Their serials were 40-2369/2377. The remainder of the B-24As on the original order were either diverted to Britain or were converted on the assembly line to later variants such as the B-24C and B-24D.
The B-24A was generally similar to the RAF's Liberator I, except for its armament of four 0.5-inch machine guns plus twin 0.3-inch guns in the tail.
These aircraft were used by the USAAC in much the same role as the RAF used the LB-30A--primarily as long-range transports. The Ferry Command B-24s were painted in the early RAF-style camouflage of dark earth and dark green over black undersides. However, during this immediate pre-war era, these planes carried large American flags painted on the sides of their forward fuselages and on the top of the fuselage, hopefully indicative of neutrality should they enter a combat zone.
Two B-24As (40-2373 and 40-2374) were used to transport the Harriman Mission to Moscow in September of 1941 via the United Kingdom. The last leg of the flight to Moscow involved a nonstop distance of 3150 miles, and from Moscow one of the USAAC B-24As continued on around the globe via the Middle East, India, Singapore, Darwin, Port Moresby, Wake Island, Hawaii, and back to Washington. The other B-24A returned to the USA via Cairo, Africa, the South Atlantic, and Brazil.
Two other USAAF B-24As were earmarked for a secret spy flight over Japanese bases on Jaluit and Truk in the South Pacific. If detected by the Japanese, the cover story for this mission would have been that the planes got "lost" while enroute to the Philippines and had accidentally strayed over the Japanese-held islands by mistake. It took a while to get these planes ready, since they had been used by the Ferrying Command and all of their combat equipment had been removed. Before the flight could be carried out, the Japanese attack on Pearl Harbor took place. One of the B-24As earmarked for this flight (40-2371) was, in fact, destroyed on the ground at Hickam field during the attack and some of the crewmembers were killed.
Interdum feror cupidine partium magnarum Europae vincendarum