A vital component of American and British strategic bombing of the Third Reich was the “oil campaign”, which targeted facilities supplying Germany with fuel, such as oil refineries, synthetic fuel factories, storage depots and other supporting infrastructure. The Romanian oil field and refinery complexes surrounding Ploesti, some 30 miles north of Bucharest, were a vital source of oil for the Axis during WWII, providing them with roughly one-third of their needs.
The Germans, alerted by a small American bombing raid in June of 1942 that met little opposition and inflicted little damage, but highlighted the potential vulnerability, surrounded Ploesti with strong antiaircraft defenses and one of the world’s densest and best-integrated air defense networks. When American bombers returned a year later, Ploesti was far more hardened than it had been in 1942, protected by hundreds of 88mm flak guns and thousands of smaller ones, plus squadrons of Bf 109 and Me 110 fighter planes.
In 1943, American air commanders drew plans for Operation Tidal Wave, a more ambitious raid against Ploesti than the paltry affair of 1942. Unescorted by fighters on what would be a 2000 mile round trip, B-24 Liberator heavy bombers of the Ninth Air Force, reinforced by bomber groups loaned them by the Eighth Force then forming in Britain, would head north from Libya across the Mediterranean, then turn northeast towards Ploesti upon reaching the Greek coast.
On August 1, 1943, which came to be known as “Black Sunday“, 177 Liberators took off from Libyan airfields for Ploesti. Maintaining radio silence and flying at 50 feet or less to avoid German radar, they skimmed over the Mediterranean, then flew at treetop level upon reaching land. However, the Germans were alerted and the raid came to grief because of a cascade of mishaps, ranging from a navigation error that took some bombers directly above a German position; a lead navigator’s crash that resulted in bomber groups arriving over the target staggered instead of simultaneously; and a bomb group leader, seeing that all formation was hopelessly lost, breaking radio silence to order the scattered B-24s to make their way to Ploesti individually and bomb as best they could.
Arriving at Ploesti, the Liberators were met by alert defenders who’d had time to prepare a warm welcome. Hundreds of antiaircraft guns, heavy machine guns, and a specially designed flak train whose cars’ sides dropped to reveal flak guns, opened up on the bombers, while fighter airplanes fell upon them. The low-flying B-24s also had to contend with smokestacks suddenly looming in their path amid the billowing smoke. Of 177 B-24s that took off that day, 162 reached Ploesti. Of those, 53 were shot down, for the loss of 660 crewmen. Of the 109 surviving Liberators that reached an Allied airbase, 58 were damaged beyond repair. The damage to Ploesti was quickly repaired, and within weeks, the oil complex was producing even more oil products than it had before the raid.