Complex sentence: His art talent led to his working an office job at division headquarters until General Shelby Burke, having seen Cardy's cartoons in an Officers Club, wanted Cardy for his own corps.
Split into simpler sentences: His art talent led to his being assigned an office job at division headquarters. This lasted until General Shelby Burke, having seen Cardy's cartoons in an Officers Club, had Cardy assigned to his own corps.