The bunker was never completed as a result of the bombings by the British and United States air forces as part of Operation Crossbow against the German V-weapons program and the Normandy landings in June 1944.

Although Adolf Hitler was at first ambivalent, he eventually became an enthusiastic supporter of the V-2 program as Allied air forces carried out increasingly devastating attacks on German cities.

Nazi Germany decided to build four giant bombproof bunkers to assemble, service and launch V2 rockets in the North of France.

The Germans' main focus of attention switched instead to Schotterwerk Nordwest, the former quarry at nearby Wizernes, where work had been ongoing to build a bombproof V-2 storage facility.

The Reservelager West in Sottevast and the Olkeller Cherbourg near Brécourt were designed to be launcher bunkers like Watten with the main building measuring about 30 by 200 metres (100 ft × 655 ft)[3] Following Operation Crossbow bombing, initial plans for launching from the massive underground Watten and Wizernes bunkers or fixed pads such as near the Château du Molay[4] were dropped and forced Walter Dornberger to develop mobile launching systems.

Organisation Todt engineer Werner Flos devised a plan under which the 5-m thick roof would be built first, flat upon the ground, and the soil underneath it would be excavated so that the construction works below would be protected against aerial attacks.

[17] In May 1943 Allied surveillance observed the construction of the first of eleven large sites in northern France for secret German weapons, including six for the V-2 rocket.