Complex sentence: Wind had now decided to enter into a military career, and he finished training as a Lieutenant on 17 June 1941, transferring to LeLv24 in August 1941, with which he participated in the Continuation War.
Split into simpler sentences: Wind had now decided to enter into a military career, and he finished training as a Lieutenant on 17 June 1941. Transferring to LeLv24 in August 1941, with which he participated in the Continuation War.