'Dredger' was a Canadian naval operation to destroy a German light warship force operating off the north-western tip of German-occupied France in the task of escorting U-boats departing from and/or returning to the port of Brest (5/6 July 1944).
During the night 5/6 July Commander D. C. Wallace’s Canadian 12th Support Group (destroyers Qu’Appelle, Restigouche, Saskatchewan and Skeena) attacked three patrol boats off Brest: V 715 was sunk after a spirited defence in which she hit the first two Canadian destroyers with many light projectiles. On passage from St Malo to Brest, the Schnellboote S 112 and S 145 rescued V 715's survivors.
The same basic task was undertaken on two other occasions shortly after this. During the night of 7/8 July the destroyers Tartar and Canadian Huron of the British 10th Destroyer Flotilla attacked craft of Kapitšnleutnant Armin Zimmermann’s 46th Minensuch-Flottille off the Channel Islands and sank M 4601 and M 4605. During the night of 14/15 July the destroyers Tartar, Canadian Haida and Polish Błyskawica sortied into area of the Ile de Croix near Lorient and sank the ex-Yugoslav submarine chasers UJ 1420 and UJ 1421.