Complex sentence: His daughter Johanna married Sir Walter St John of Lydiard Tregoze and was the grandmother of Viscount Bolingbroke, By his second wife he had two children, and after her death he married, in 1645, Elizabeth, daughter of Daniel Oxenbridge.
Split into simpler sentences: His daughter Johanna married Sir Walter St John of Lydiard Tregoze and was the grandmother of Viscount Bolingbroke. After her death he married, in 1645, Elizabeth, daughter of Daniel Oxenbridge.