Complex sentence: When Walker was a child the fate of his uncle Laurie was never discussed and it was only by using his skills as a historian that Walker discovered that his uncle had volunteered for service with the thirteenth squadron of the RAAF.
Split into simpler sentences: When Walker was a child the fate of his uncle Laurie was never discussed. By using his skills as a historian that Walker discovered that his uncle had volunteered for service with the thirteenth squadron of the RAAF.