After successfully defending the IBU and "Ring Magazine" middleweight titles 11 times, Thil fought Fred Apostoli in a non-title bout on September 23, 1937, in New York City. It was a non-title affair because the New York State Athletic Commission, which recognized Freddie Steele as world middleweight champion, said they would sanction the fight only if Thil agreed not to put his championship on the line. Apostoli won by a 10th-round technical knockout (TKO). The fight was stopped due to a severe cut over the right eye of Thil, who was ahead on points at the time of the stoppage. Shortly after the loss, the 33-year-old Thil retired from boxing vacating his titles.