13 June 1943: On Mission Number 63, 76 VIII Bomber Command Boeing B-17F Flying Fortress four-engine heavy bombers of the 4th Bombardment Wing were sent to attack the U-boat pens at Kiel, Germany.
German submarine attacks on transatlantic convoys were a major threat to the Allies. England was dependent on North America for food, fuel, munitions and weapons. Destruction of the submarine bases and repair facilities was therefore a very high priority for VIII Bomber Command. These were often very heavily reinforced concrete bunkers where submarines could be serviced and repaired, safe from air attack.
The “Kilian” base at Kiel was for the protection of up to 12 newly-built U-boats. Each bay was 138 meters (453 feet) long and could house two submarines, end-to-end. The roof was 4.8 meters (15 feet, 9 inches) of reinforced concrete, and the walls were 3.3 meters (10 feet, 10 inches) thick.
60 bombers made it to the target but were met with the heaviest fighter attacks to that point of the war. 22 B-17s were shot down. Of those that returned to England, 24 were damaged, 1 so badly that it was beyond repair.
3 airmen were killed, 20 wounded and 213 were listed as Missing In Action.
Before the war, it was thought that the defensive machine guns of the Flying Fortress would be able to protect it against enemy fighters, but losses like those suffered in this raid proved the necessity for escorting fighters to defend the bomber formations.
NOTE: A very detailed analysis of this mission, “USAAF Mission #63: Bremen and Keil” by Andreas Zapf can be found at
17 August 1943: Mission No. 84. One year after the Eighth Air Force first attacked occupied Europe with its B-17 Flying Fortress four-engine heavy bombers, a mass attack of 376 B-17s attacked the Messerschmitt Bf-109 factory at Regensburg, Germany, and the ball bearing factories at Schweinfurt.
Over Germany for over two hours without fighter escort, 60 bombers were shot down and as many as 95, though they made it to bases in Allied territory, were so badly damaged that they never flew again. 55 air crews (552 men) were listed as missing in action.
Of the 146 B-17s of the 4th Bombardment Wing which attacked Regensburg, 126 dropped their bombs, totaling 298.75 tons (271.02 Metric tons), destroying the factory and seriously slowing the production of the Messerschmitt Bf 109 fighter. After the attack, the 4th Bomb Wing headed for bases in North Africa. 122 B-17s landed there, half of them damaged.
The 1st Bombardment Wing (Heavy) sent 230 B-17s to Schweinfurt. Weather delays caused the planned diversion of two separate attacks to be unsuccessful. Cloud buildup over the Continent forced the bombers to fly at 17,000 feet (5,182 meters), nearly 10,000 feet (3,048 meters) lower than planned, increasing their vulnerability. Just 183 bombers made it to the target and dropped 424.3 tons (383.9 Metric tons) on the five factories in the target area. Then they headed back to their bases in England, under fighter attack most of the way. The 1st Bombardment Wing lost 36 bombers.
Though the raid did cut production of ball bearings as much as 34%, the losses were quickly made up from stockpiles. The two attacking forces succeeded in shooting down 25–27 German fighters.