The power station at Rjukan, Norway had been adopted by the Nazis for the production of ‘heavy water’ for use in its nuclear programme. The Allies had no clear knowledge of how far the German nuclear programme was progressing and the power station remained a top priority target. Previous efforts to destroy the plant had used special forces from SOE. Operation Gunnerside, guided by local members of the Norwegian resistance, had had some success.
However it was now decided that a bombing raid was needed to deal with the plant once and for all. It was hoped that a daylight bombing raid by the 8th Air Force could be accurate enough to minimise civilian casualties. The raid was timed to take place during the lunch hour, in the expectation that many of the civilian workers would be absent.
Two waves of bombers were sent in, first the B-17s which dropped 435 tons of bombs but only achieved four hits on the factory itself. The second wave of B-24 were very accurate insofar as most of their bombs hit the target they attacked. Unfortunately it was the wrong target, a chemical plant three miles away.
This was the mission report of the 392nd Bomb Group, whose B-24s formed part of the second wave of bombers:
The target for this mission was the hydro-electric power station at Rjukan, about 75 miles due west of Oslo. Assembly for this long-range mission was far from normal due to extremely poor weather. Sporadic instrument conditions prevailed from 1,000 to at least 23,000 feet. Cloud cover coupled with icing conditions resulted in several planes not finding their formation.
The 392nd BG briefed 21 crews; 2 did not take off due to mechanical problems. Another 6 planes aborted in the air: 2 (Clover in #537 and Gonseth in #485) had joined the 44th BG formation and returned when they did; 2 (Reade in #478 and Baumgart in #510) could not find any formation to join; and 2 (Hull in #135 and Voght in #626) had mechanical problems.
The 392nd had assembled its remaining 13 planes before reaching Cromer, going to 20,000 feet to accomplish the task. Several individual planes joined in to form a composite formation, which the 392nd followed to the secondary target. As they made the second run, the 392nd made a wider swing to the east, lost them, came back to the east and made a run on the target. Clouds obscured the target intermittently.
Bombs were dropped from 14,000 feet at 1212 hours. Photo analysis on return showed that 29.5 tons of bombs were dropped on the Norsk Hydro Nitrate Plant three miles east of the secondary with only 2.5 tons dropped on the hydro-electric plant. This was unfortunate, as the bombing was excellent. Using the center of the large centrally-located building as an MPI, the 392nd had 37 percent of its bombs within 1000 feet and 85 percent within 2000 feet.
No enemy aircraft were encountered and the Group suffered no aircraft losses or casualties. This raid was to be one of the longer ones flown by the 392nd with a total of 9:30 hours duration.
The raid was considered to be a success. Although only a small proportion of the bombs dropped hit the plant, those that did hit caused sufficient damage to cause the Germans to stop production at the plant. Nevertheless there were casualties amongst local civilians, a matter which caused the Norwegian Government in Exile to lodge a formal protest.