sentence: zeebrugge raid on the night of 22 -- 23 april 1918 , the zeebrugge raid began when an armada of british sailors and marines led by the old cruiser , , attacked the mole at zeebrugge , belgium , in order to negate the serious threat to allied shipping , that was being posed by the port being used by the imperial german navy as a base for their u-boats and light shipping .