Operation Tidalwave, the attack on the oil refineries at Ploesti on 1 August 1943 was the most famous bombing mission performed by the Consolidated B-24 Liberator. The complex of oil facilities at Ploesti was the largest individual supplier of oil and petroleum to the German war economy. In 1943 it was estimated that sixty percent of Germany’s crude oil came from Ploesti, and that two thirds of German’s petrol was produced from crude oil, so the Ploesti refineries were responsible for some forty percent of German petroleum. The Ploesti oil fields had an annual capacity of nine millions tones, serviced by nine main refineries.
Ploesti had been attacked before. Soon after the German invasion of Russia, Soviet aircraft had attacked, and they were to return in September 1942. The Americans made their first visit on 11-12 June 1942, when thirteen B-24s based in North Africa had destroyed one oil depot. These raids had alerted the Germans to the risk to Ploesti, and by the summer of 1943 it was already one of the best defended targets in Europe, ringed by a formidable array of anti-aircraft guns and with both German and Romanian fighter units based in the area.
Having decided to attack Ploesti, the USAAF then had to decide which aircraft and units to use, and how to attack. It was decided to make a low level attack with heavy bombers, in the hope of maintaining surprise. This meant that the aircraft used would have to be the Consolidated B-24 Liberator, for the B-17 did not have the range to reach Ploesti from North Africa at low level. Two B-24 units, the 98th and 376th Bombardment Groups were already present in North Africa. Two more were detached from the Eighth Air Force in England (the 44th and 93rd) while a fifth unit, the newly formed 389th Bombardment Group was diverted from the Eighth almost immediately after arriving in England. Together the last three units formed the 201st (Provisional Wing) and began to practice low level flying over Norfolk.
A number of changes needed to be made to the B-24Ds. Their high altitude Norton bombsight needed to be replaced with low level sights. Extra fuel tanks were installed. The ball-turret gunner was left behind to save weight, and because it was not expected to be of any use during the low level, high speed attack. A great deal of attention was given to the type of bombs to be used. In the end 311 tons of 1,000lb and 500lb demolition bombs, 290 boxes of British incendiaries and 140 clusters of American incendiaries were carried. All of the demolition bombs were given delayed action fused, with time delays varying from between one and six hours in the first and second waves and 45 seconds for the final waves.
The British based aircraft left for North Africa at the end of June. During the first half of July they flew operations to support the invasion of Sicily, ending with a raid on Rome. On 20 July dedicated training for the raid on Ploeti began. Over the next two weeks the training missions increased in scale, until eventually a full scale dress rehearsal was carried out, against a mock-up of the target built in the desert.
The plan was for the five groups to travel in formation all the way from North Africa to the town of Pitesti, sixty-five miles from Ploesti. At that point the 389th Bombardment Group, the last of the five groups, would turn slightly to the left to attack its target at Campina. The remaining four groups would fly on to Floresti, where they would turn right towards Ploesti. All four would hit their targets at Ploesti and Brazi at the same time, and then turn right again to begin the journey home.
The first aircraft took to the air at 7.00 on the morning of 1 August 1943. The plan began to unravel when the formation reached the Albanian and Yugoslavian mountains. Thick clouds prevented the formations from taking their preferred lower level route through the mountains and by the time the aircraft reached the target area there was a sixty mile gap between the first two groups and the rest of the formation. At the first initial point (Pitesti) the 389th left the main formation as planned, while the entire formation dropped down to 500 feet.
Two of the remaining four groups failed to reach the second initial point at Floresti. By now the lead 376th Bombardment Group had lost both its first and second lead aircraft, leaving the navigation duties to the third aircraft. What happened next was a clear demonstration of the difficulties of even daylight navigation over unknown territory. The 376th Group mistook the town of Targoviste for Floresti, and turned right far too soon, followed by the 93rd Bombardment Group, which had kept in touch with them over the mountains. The 44th and 98th Bombardment Groups identified the correct town at Floresti, and followed the original plan of attack, but without the element of surprise.
The 376th and 93rd flew south east until they reached the outskirts of Bucharest before realising their mistake. They then turned north and approached Ploesti fro the south, but the damage was done – Bucharest was the headquarters of the Romanian air defences, and the defenders of Ploesti were alerted before the American bombers could reach their target.
At the southern edge of Ploesti the 376th and 93rd Groups encountered very heavy anti-aircraft fire. General Ent, flying with the 376th, ordered the group to fly anti-clockwise around Ploesti to attack from the north east. Once again they encountered heavy anti-aircraft fire, and Ent ordered them to attack targets of opportunity. Despite all of this chaos, six aircraft led by Major Norman C. Appold actually hit their assigned target, while the rest of the formation was able to find suitable targets. Somewhat ironically the 376th suffered the lowest number of losses of any unit, losing three aircraft over the target.
The 93rd encountered the same heavy fire south of Ploesti, but decided to fly straight on, attacking targets on the southern side of the city. Unfortunately, those targets were the Astra Romana, Unirea Orion and Colombia Aquila refineries, all targets allocated to the 98th and 44th Groups. The attack by the 93rd caused significant damage to these targets, but also left a number of the unexploded delayed-action bombs waiting to explode. The 93rd lost eleven aircraft over the target.
At about the same time as the 93rd was attacking Ploesti, the 98th and 44th groups reached their initial point, and turned right to make their attack. They arrived to find the defences of Ploesti fully alerted, but still made their attacks. Unfortunately they were attacking the same targets as the 93rd, and a number of their B-24s were destroyed by explosions caused by delayed action bombs from the earlier attack. These last two groups were also badly hit by German and Romania fighter aircraft on the way back to North Africa. According to the official USAF history of the war, the 98th lost 21 aircraft and the 44th lost eleven.
The 389th, attacking Campina, made the most successful attack, virtually destroying its target, for the lowest losses amongst the four groups that attacked a set target.
The official history gives the losses during Tidal Wave as 54 aircraft lost, 41 of them lost in action, with 532 airmen killed, prisoners, missing or interned. Surviving aircraft landed at basses on Malta, Sicily and Cyprus as well as in neutral Turkey. The attack itself caused serious damage at Ploesti, destroying 42% of the refining capacity and 40% of the cracking capacity. The cracking capacity was reduced for between four and six months, but the refining capacity recovered much more quickly than expected, as the refinery had been operating somewhat below its full capacity, with the result that there were unused refinery units that could be activated. At this point in the war no plan had been put in place for repeated attacks on the oil industry and Ploesti would be left along until the spring of 1944.
Although it had not quite lived up to expectations, the attack on Ploesti was still one of the most impressive individual air raids of the entire Second World War. Every single crew member received the DFC for their part in the mission, all five groups received Presidential Unit Citations and five Medals of Honor were awarded, three of them posthumous. The crews of the B-24s had flown for over a thousand miles to reach their target, pressed home their attacks against determined and forewarned opposition, and then flow another thousand miles back to safety, under heavy fighter attack.