This was a German series of undertakings by small coastal craft, including Linsen explosive boats, to interrupt Allied maritime supply operations off the coast of Belgium and the Netherlands (5 October/1 November 1944).
On 5/6 October the first of the attacks, in this instance by the 214th Kleinkampf-Verband using radio-controlled Linsen explosive motor boats (operating in three-boat units with two explosive-laden unmanned craft and one manned boat carrying remote-control gear), was launched from Vlissingen (Flushing) against Allied minesweepers involved in the clearance of the Scheldt river estuary and thus the opening of the port of Antwerp, and also in the hope of running supplies to the beleaguered German garrison of Dunkirk. Both halves of the undertaking failed in the face of adverse weather rather than the Allied defences. Some 36 Linsen boats were lost and another 14 had to be abandoned, and just 12 returned to base.
Another attempt was made on 24 October, this time by 60 Linsen boats of the 215th Kleinkampf-Verband. The undertaking was effectively defeated by Allied artillery fire, which caused a dispersal of the Linsen boats, of which only 19 returned to base.
Yet another attack took place on 27 October in the Scheldt river estuary, and achieved the destruction of some Allied light craft.
The final undertaking took place during the night of 31 October/1 November, when the Linsen boats of the 215th Kleinkampf-Verband made an attack in which the Germans claimed, without verification, the destruction of a 2,000-ton vessel carrying ammunition. On this night elements of a Polish armoured formation approached Vlissingen, and the Linsen boat base was abandoned as the Germans evacuated the port.