​​Mimoyecques Fortress​

Mimoyecques Fortress is a former Second World War V3 bunker located in the commune of Landrethun-le-Nord in the Pas-de-Calais department.

The V3 or multiple charge gun is a 127-metre-long gun developed by the engineer August Coenders, that could fire 150 mm shells. Additionally, an extra 32 explosive charges, placed in lateral chambers, increased the speed of the shell at the exit of the gun's mouth to 1550 metres per second, with a range of 165km. The site had to be constructed on several levels to shelter this immense cannon and to protect it from Allied bombings.

The site was chosen by the Todt Organisation for its geographical position (150km from London) and its geological structure.

The first workers (German engineers, miners from the Ruhr and Soviet prisoners) arrived on the site in June 1943. In September 1943, a 600-metre-long and 30 metres deep railway tunnel was completed to supply the site. The workers then immediately began digging the lateral galleries and the level 100 metres below which served as the loading base for this super gun. Five shafts for five guns were planned to fire up to 1,500 shells per day at London.

The Allies knew about the existence of the Mimoyecques site as early as 18 September 1943. The first two bombings were carried out on 5 and 8 November 1943. Between November 1943 and the spring of 1944, sixteen air raids targeted the fortress. Despite the 4,100 tonnes of bombs dropped on the site, the damage was insignificant because the bombs used at that time were not powerful enough to penetrate the 30 metres of chalk and the 5 metres of reinforced concrete.

However, the attack of 6 July 1944 was decisive: 16 Lancasters of No. 617 Squadron dropped heavy Tallboy bombs on the fortress. Eight of them hit the target. The -100 level was completely flooded, tunnels and shafts collapsed, and hundreds of slave workers were entombed underground. Construction works were abandoned by the German troops, and on 5 September 1944 the site fell to the Canadian troops without any resistance.