The oil fields located around the city of Ploesti were of vital importance to Germany's war effort. They were the first targets in Europe to be bombed by American forces from their bases in Egypt in June 1942. These facilities were also the target of massive raids consisting of 220 Liberator bombers in August 1943. The raids took place from bases in Lybia. However, the main offensive started in April 1944, when Allied forces from bases in Southern Italy could attack in larger numbers and with greater payloads.
The main targets of these attacks on the oil industry were refineries, storage areas, as well as the means of transport for the oil - railroad facilities and Danube ports.
Axis forces started to strengthen their defenses after the first attack.
Defenses consisted of many antiaircraft guns, from light 20mm for low-level targets, up to the well-known 88mm Flak, and 105mm and 128mm guns. These guns were directed by German Wurtzburg radars.
Vital installations were also protected by smoke projecting machines, that would cover the target in thick smoke, obscuring it from aerial view.
The Germans brought in their Me-109 fighters and Me-110 night fighters, while the Romanians used their IAR-80/81 fighters, which were often confused by American crews as the similar-looking German Fighter Fw-190. At one point, the Germans deployed Fighter Group JG53 to Niš airport, where it's task was to hunt down lone damaged American bombers.
Over Romania, the Allies lost more than 300 planes, with 1,706 killed and 1,123 airmen taken prisoner. In Yugoslavia, over 100 planes flying missions to Romania crashed, with a total of over 900 airmen. The majority of them were rescued by Chetnik and Partisan guerrillas.
Heaviest 128 mm flak guns were mounted on railroad cars for better mobility
German Wurzburg radar
Smokescreen covers target, hiding it from aerial view.