On 19 July, III./JG 51 were confronted by Defiants of No. 141 Squadron south of Folkestone. As the German pilots were now aware of the Defiant's lack of forward armament, they soon gained the advantage in combat and claimed 11 Defiants shot down in 8 minutes. Oesau was credited with one Defiant, taking his score to 19. He was the first one of JG 51 to reach double digits in World War II. RAF losses record six Defiants destroyed and two damaged.