However, it never went into operation due to intensive Allied bombing that made it the most heavily attacked of all the German V-weapon sites, and also of all military targets in Europe during World War II.

With the Allies gaining air superiority by 1943, different sections of the Luftwaffe – which had responsibility for the V-1 – debated how best the weapons could be deployed in the face of an increased threat of aerial bombardment.

In July 1943, Luftwaffe chief Hermann Göring brokered a compromise under which both alternatives would be pursued; four (and ultimately ten) heavy launch bunkers would be built along with 96 light installations.

[2] The German engineers adopted a new method which they called Verbunkerung, which involved first building the roof flat on the ground then excavating beneath it – sheltered from bombs – to create the rest of the facility.

[1][3] The bunker would have been linked with the main railway line from Saint Pol to Abbeville, enabling trains carrying V-1s and supplies to enter the body of the structure.

[3] The Allies spotted the construction of the Siracourt bunker almost as soon as it began in September 1943, when two parallel trenches were dug and concreted to form the walls of the structure.

Before the land was leveled, 80 German prisoners of war removed the launching ramp facing England and partially filled in the interior of the bunker.