This was a British naval undertaking to lay a defensive minefield in the Wash (5 July 1940).
The ships involved were the coastal minelayers Plover and Dutch Willem van de Zaan. This was part of the British naval scheme to protect the east coast of England, which was seen as a probably location for any German invasion. The 1,020-ton Plover was a coastal minelayer ordered in 1936 from Denny of Dumbarton and laid down on 7 October of the same year for launch on 8 June 1937 and commissioning on 24 September of the same year.
After completion, the ship was deployed as a tender to the Torpedo School Vernon at Portsmouth and used in the British programme to develop and evaluate new designs of sea mine. The ship was designed to carry 100 mines and was deployed throughout World War II for minelaying in the coastal waters of the UK and North-West Europe. Plover was not intended for laying mines in open waters such as the North Atlantic.
After initial wartime service on the east coast of Scotland and Strait of Dover, the ship was prepared at Portsmouth in the period up to May 1940 for use in the laying of the East Coast Barrier. Plover began minelaying in the East Coast Barrier with the auxiliary minelayer Teviot Bank in the 'BS.10' to 'BS.20' operations up to 2 July. The ship was then used in 'AW' in the Wash with the Dutch van der Zann before being transferred back to the Strait of Dover, after which she returned to the east coast on 30 July for the 'BS.30 to 'BS.36' and 'BS.40' to 'BS.45' operations into November, when the ship steamed to the Humber for refit.