The B-24 Liberator first arrived in the Mediterranean during the crisis in North Africa in the summer of 1942. Part of the American reaction to this crisis was to move General Lewis Brereton from India, with as many heavy bombers as he could find. The result was the creation of HALPRO, a detachment of 23 B-24Ds under the command of Colonel Harry H. Halverson. This detachment had originally been earmarked for an attack on mainland Japan from China, but instead found itself operating from Egypt.
On 11-12 June 1942 HALPRO entered combat, when thirteen B-24Ds attacked the oil refineries at Ploesti. Ten of these aircraft managed to hit their target, destroying one oil depot, but the aircraft scattered across the Middle East on their return journey, landing in Iraq, Turkey and Syria.
The remnants of HALPRO fought on in the Middle East, until in July 1942 it became part of the 376th Bombardment Group, soon joined by the 98th Bomb Group. These two B-24 units would remain in the Mediterranean for the rest of the war, first with the Ninth Air Force, then with the Twelfth and finally with the Fifteenth.
For the moment the two groups operated from bases in Palestine, attacking targets off the north coast of Africa, as well as supporting the fighting at El Alemain. During 1943 the fighting moved to the west, and the two B-24 units flew operations over Sicily and southern Italy. For large parts of 1943 the two B-24 units were joined by the first three B-24 units to have joined the Eighth Army, the 44th, 93rd and 389th Bombardment Groups. Some or all of these units supported the invasion of Sicily and the Salerno landings while all five B-24 units in North Africa took part in Operation Tidalwave, 1 August 1943, the low level attack on the oil refineries at Ploesti.
Once the scattered forces used to attack Ploesti were back together, operations over Italy began again, with a raid over Foggia on 16 August 1943. Soon after this the American air forces in the Mediterranean were reorganised with the formation of the Twelfth Air Force. The two B-24 units of the Ninth Air Force transferred to the Twelfth, flying their first mission with the new unit on 1 October 1943, against the Messerschmitt Bf 109 factory at Wiener Neustadt.
In November 1943 the Twelfth Air Force was split in two, with the heavy bomber units forming the new Fifteenth Air Force, under the command of Major General James Doolittle. This new air force had 90 B-24s and 210 B-17s, and so for the first months of its existence the B-17 performed the majority of bombing missions, with the B-24 attacking specialist targets. The new air force’s first mission came on 2 November 1943, when a force of 137 B-17s and B-24s attacked the Messerschmitt Bf 109 factory at Wiener Neustadt. The build-up of Liberator units began in December, and between then and May 1944 another thirteen B-24H and B-24J equipped units joined the Fifteenth Air Force, bringing the total to fifteen. On 3 January Major General Nathan F. Twining took command of the Fifteenth, retaining command to the end of the war.
The B-24s of the Fifteenth Air Force operated across most of southern and eastern Europe, Austria and southern Germany, performing strategic bombing missions, and also operated in support of the Allied armies fighting in Italy.
In January-March 1944 the Fifteenth operated in support of the Anzio landings. Before the landings its B-24s attacked German transport links in central Italy, returning to those targets again after the landing bogged down. The heavy bombers were also used to attack German troop concentrations outside the Anzio beachhead.
The most controversial mission for the Fifteenth Air Force came on 15 March 1944, when a large force of heavy bombers destroyed the abbey of Monte Cassino in the belief that it was being used by the Germans.
The B-24s of the Fifteenth Air Force made a contribution to Operation Argument, the attack on the German aircraft industry (also known as “Big Week”), mounting raids against German aircraft factories on 22, 23 and 25 February 1944. Attacks on the aircraft industry would continue throughout the war.
April 1944 saw the beginning of two campaigns – the concerted attack on the German oil industry, and the preparation for Operation Anvil, the invasion of Southern France. Aircraft of the Fifteenth Air Force attacked more than 80 different oil refineries, many of which were out of range of British based bombers.
Operations in support of Operation Anvil began on 28 April 1944, with an attack on Toulon, and continued after the invasion itself began on 15 August. June 1944 also saw the Fifteenth begin operations to support the Soviet armies as they entered Romania.
During the battle of the Bulge of December 1944-January 1945 the B-24s of the Fifteenth Air Force launched a series of raids on the German troops in northern Italy, designed to prevent them being moved to the Ardennes.
The attack on the German aircraft industry continued into March 1944, when on 12 March 366 Liberators attacked the Jet factory at Neuberg, almost destroying it. Three days later the Fifteenth Air Force attacked Berlin for the first time.The last B-24 missions of the Fifteenth Air Force were flown on 26 April 1945, and were a series of attacks on the German lines of communication in Austria and through the Brenner Pass, designed to prevent German troops escaping from Italy to reinforce a possible last stand in southern Germany.