After France surrendered, František fled to Britain and after training on 2 August was assigned to Polish No. 303 Squadron based at RAF Northolt, flying Hawker Hurricane fighters. František was used to obsolescent aircraft with fixed landing gear, and on 8 August at the end of a training flight, he forgot to lower his Hurricane's retractable undercarriage and accidentally made a belly landing. He was unhurt, and the aircraft was repairable. The squadron entered action in the last phase of the Battle of Britain. František's first confirmed victory was shooting down a Messerschmitt Bf 109E fighter on 2 September 1940. His fifth victory nearly cost him his life. On 6 September he shot down a Bf 109E of &lt;a href="Jagdgeschwader%2052"&gt;III/JG 52&lt;/a&gt; near Sevenoaks in Kent, but František's Hurricane was damaged so badly that he had to make a forced landing near Falmer.