Complex sentence: In 1764, his elder brother August William died, at which point Frederick Charles Ferdinand inherited Brunswick-Bevern and also became provost of St. Blaise and St. Cyriacus Abbey in Brunswick.
Split into simpler sentences: In 1764, his elder brother August William died, and Frederick Charles Ferdinand inherited Brunswick-Bevern. He also became provost of St. Blaise and St. Cyriacus Abbey in Brunswick.