How many German aircraft did the Defiant claim over Dunkirk in a single day?

The Defiant got off to an effective start against enemy aircraft, and its best day was 29 May, when No. 264 Squadron claimed 37 kills in two sorties: 19 Ju 87 Stukas, most shot down as they pulled out of their dives, nine twin-engined Messerschmitt Bf 110 heavy fighters, eight Bf 109s and one Ju 88. On 27 May, the same squadron had claimed three He 111s shot down and two more damaged.

Although 264 Squadron claimed 48 kills in eight days over Dunkirk, the cost was high: 14 Defiants lost. Actual German losses were no more than 12-15 enemy aircraft. The turret's wide firing arc meant several Defiants could engage the same target, resulting in multiple claims for a single aircraft.

German fighters suffered losses when diving onto Defiant formations from behind, apparently mistaking them for Hurricanes. The Luftwaffe eventually changed tactics to outmanoeuvre the Defiant and attack it from below or head-on, directions in which the turret's machine guns could not be aimed and offered no defence at all.