During the last months of 1939, and the first of 1940, German submarines attacked allied ships, mainly in the Atlantic Ocean. The range of the German submarines was limited, and they had no ability to attack the very important allied convoys sailing to Murmansk in Russia. In addition to the U-boat bases in France and Biscay, the Germans needed bases in Norway to be able to really hurt the allied shipping.

After the invasion of Norway, it was decided to build U-boat bases in Trondheim and Bergen.

In May 1942 construction started on a massive U-boat bunker in Bergen. It contained 7 pens, and had a 6 meter thick roof and walls 2.5 to 4 meters thick. The U-boat bunker was planned to be completed in July 1945. The bunker was located in Laksevag, a short distance from Bergen's main harbour.

The 11.Unterseebootsflottille was formed in mid 1942 and was stationed in Bergen. By the end of the war it had been assigned over 190 U-boats of VII, XXI and XXIII type, extended the range of U boat operations and caused substantial allied shipping casualties.

When the Germans withdrew from France in 1944, the French based U-boats were transferred to Norway and caused a major threat to the allied convoys in the North Sea and to shipping supporting the French landings.

One of the roles of Coastal Command was to keep the U-boats in their base, safe from attack by Allied Aircraft and naval vessels. However, destruction of the U-boats and their bunker was a desirable objective for the Allies. The bombing raid on the bunker in 1944 was to become one of biggest tragedies in Norway during WW2.

4 October 1944.

The first planes were observed at 09.05. 93 Halifax and 47 Lancasters approached the target from the west and turned north over the city and bombed. Most aircraft were to bomb the U-boat pens but 14 Halifax and 6 Lancasters were targeting individual U-boats in the harbour.

The bombing became scattered and little damage was done to the U-boat pens (7 bombs hit doing little structural damage but putting the electrics out of commission, nearby ship yards were badly damaged and 3 U-boats were damaged but did not sink). The remaining bombs fell across the town and hit everywhere. On the ground it seemed as though the RAF was carpet bombing the whole of Laksevåg. One of the bombs hit Holen skole, just over 260 metres from the U-boat pens. It crashed through the roof and exploded over the air-raid shelter that was housing 350 children, teachers and men from the civil air defence. The rescue teams and fire fighters who found the dead children said that at the instant of death some of the children had clung to their teachers and were now nearly impossible to remove. Others died under collapsing walls and of suffocation.

It is impossible to imagine the dreadful seconds in the shelter, when the lights went out, and the panic started among the children. 61 children, 2 teachers and 16 men from the civilian air defence died on Holen Skole that day.

A total of 193 Norwegian civilians died as a result of the raid, 180 were wounded, 60 houses were totally destroyed and over 700 people were made homeless.

The Germans lost 12 men, 3 U-boats (damaged or destroyed: U-228 and U-993) and at least one auxiliary boat (E. Bornhofen) sunk and two more damaged. It is believed that a few Russian POW’s working on the bunker were killed too, but this is not confirmed. One Lancaster was last on this raid.

During the raid 1260 1000lb kg bombs and 172 500lb kg bombs were dropped in 11 minutes. The raid had been a partial failure and the RAF would return.

29th October 1944

A second raid took place with 244 aircraft (237 Lancasters and 7 Mosquitoes). Due to dense clouds only 47 dropped their bombs before the raid was aborted. Four hits were recorded to the U-boat pens without causing further damage. Bombing again became scattered and fell in the main town area killing a total of 52 civilians and 2 Germans. 3 planes were shot down on this second raid.
The second raid had been a failure.

12th January 1945

This time 32 Lancasters of 617 and 9 Sqns loaded with Tallboy “Earthquake” bombs weighing approx 10,000 lb and one Mosquito were tasked to bomb the U-boat pens and the harbour. The accuracy of the bombing was greatly improved; three tallboys found their primary target and penetrated the bunker. One penetrated the roof, causing an 8 meter wide crater on the top and a 4 meter crater inside! Great damage was caused to workshops, offices and stores within by the bomb strikes. 2 U-boats (U-775 and U-864) were slightly damaged, a minesweeper sunk and a transport ship damaged. 20 Germans were killed and no Norwegian casualties were reported.

In the harbour the minesweeper M1 was steaming towards Helleneset (Away from Bergen), trying to avoid the Lancasters. One Lancaster decided to go for the minesweeper and managed to hit the boat. It is probably the only time a minesweeper was hit by a Tallboy! 20 of the crew of 34 were immediately killed.
Three Lancasters were lost on this raid.

The allies damaged but did not manage to destroy the bunker during the war. Today the bunker is used by the Norwegian Navy to maintain and repair submarines. Holen skole was demolished and rebuilt in 1958. Today there is little left to remind about the accident in 1944 except the U-boat bunker 300 meters away.