The weapon was planned to be used to bombard London from two large bunkers in the Pas-de-Calais region of northern France, but they were rendered unusable by Allied bombing raids before completion. Two similar guns were used to bombard Luxembourg from December 1944 to February 1945.
The V-3 was also known as the Hochdruckpumpe (“High Pressure Pump,” HDP for short), which was a code name intended to hide the real purpose of the project. It was also known as Fleißiges Lieschen (“Busy Lizzie”).
The V-3 project intended to use two batteries to crush London under a barrage with hundreds of shells per hour. The shells weighed 310 lbs. and had a 55 pound explosive charge.
On 4 July 1944, the V-3 located in Mimoyecques, Northern France was test-fired with 8 rounds (one of the 5.9 ft long shells travelled 58 miles). However, the gun burst during the testing…putting an end to the tests.