Complex sentence: Defoe died in poverty, and the grave was marked with a simple headstone; and in the winter of 1857/8--at a time when the burial ground was closed and neglected--the grave was struck by lightening and the headstone broken.
Split into simpler sentences: Defoe died in poverty, and the grave was marked with a simple headstone. In the winter of 1857/8--at a time when the burial ground was closed and neglected--the grave was struck by lightening and the headstone broken.