When France capitulated in 1940 Stehlík was evacuated to Britain, where he joined the Royal Air Force Volunteer Reserve.

Stehlík was restricted to civilian jobs until 1964, when the Communist government politically rehabilitated him and granted him a retired military rank.

On 29 September 1938 France and the United Kingdom signed the Munich Agreement, which forced Czechoslovakia to cede the Sudetenland to Nazi Germany.

On 15 March 1939 Germany occupied Czechoslovakia and imposed the Protectorate of Bohemia and Moravia, which the next day dissolved the Czechoslovak armed forces in its territory.

On 1 December he was posted to Groupe de Chasse III/3 which was equipped with Morane-Saulnier M.S.406C.1 fighter aircraft and later re-equipped with the more advanced Dewoitine D.520C.1.

Stehlík and other Czechoslovak airmen were evacuated to the United Kingdom, where they were quickly enlisted in the RAF Volunteer Reserve.

About 16:00 hrs on 8 October a lone Luftwaffe Junkers Ju 88 medium bomber of Kampfgeschwader 2/806 was sighted flying up the River Mersey.

At 16:15 the bomber made a forced landing in a field near Bromborough Dock and the surviving crew were captured.

From January 1942 until February 1943 he served at Elementary and Secondary Flying Training Schools in Canada.

Early in 1944 Stehlík joined the 1st Czechoslovak independent fighter aviation regiment in the Soviet Union.

[4] From 15 September 1944 Stehlík was based at Tri Duby airfield in central Slovakia, fighting in the Slovak National Uprising.