 After the German invasion of the Soviet Union began on 22 June 1941, German forces advanced rapidly through the Soviet-occupied Baltic states, and by the end of August the Estonian capital of Tallinn was surrounded by German forces, while a large part of the Red Banner Baltic Fleet was bottled up in Tallinn harbour.In expectation of a Soviet breakout, the Kriegsmarine and the Finnish Navy had started on 8 August 1941 to lay minefields off Cape Juminda on the Lahemaa coast.While Soviet minesweepers tried to clear a path for convoys through the minefields, German coastal artillery installed a battery of guns near Cape Juminda and the Finnish navy gathered their 2nd Motor Torpedo Boat Flotilla with patrol boats VMV9, VMV10, VMV11 and VMV17.