Seeking naturalization record for Friedrich Schiller

I have searched for my uncle before but unfortunately, I found an error in my search because of an incorrect birth date and place. My uncle, Friedrich Schiller, was born on 15 December 1905 in Mar. Ostrau Austria. As a young man he lived in Gablonz a.N. Bohemia (which was absorbed into the German Empire in 1938). In early 1938 he went to England after the occupation of the Sudetenland (part of today's Czech Republic) and in late 1939 was detained as an Enemy Alien prisoner on the Isle of Man. On 3 July 1940 he was put on a Prisoner Ship called S.S. ETTRICK and sent to Canada. There he was again held as an Enemy Alien prisoner until April 1942. I believe he then migrated to the United States, but we lost all knowledge of him until early 1947 when we received a letter from him asking my mother and her 3 children to move to America.  She decided not to go for reasons I am not aware of. I am now 81 years old and started Genealogy about 10 Years ago so unfortunately, everyone I could have asked for information about my uncle are now dead. All I do have, are copies of the British Enemy Alien papers from that time. I would very much appreciate any help to find my uncle’s family so I can finally know what happened to him and connect with his remaining living relatives.  With thanks