It was a dark and somewhat stormy night. In the western English Channel, off the Ile de Batz, twelve destroyers, eight Allied (including two Canadian) and four German, hurtled towards each other at a combined speed of 47 knots. Radar, penetrating the black murk ahead of the Allied ships, detected hostile contacts at ten miles range and the force deployed for action. Minutes later they opened devastating fire upon a startled enemy.
The battle that ensued on the night of 9 June 1944 was the raison d’etre of the 10th Destroyer Flotilla, a destroyer strike force based on Plymouth. When planning the Normandy invasion Allied naval commanders recognized that although Kriegsmarine surface forces represented only a limited threat to the beachhead, powerful destroyers based in Bay of Biscay ports could wreak havoc on vulnerable build-up convoys crossing the Channel. But, because of the dominance of Allied air power, enemy destroyers came out only in the hours of darkness. Therefore, to win control of the western Channel, the 10th DF had to master the difficult art of night fighting.
Whitby, Michael "Masters of the Channel Night: The 10th Destroyer Flotilla’s Victory Off Ile De Batz, 9 June 1944." Canadian Military History 2, 1 (1993)