Complex sentence: James made one serious attempt to recover his crowns from William and Mary when he landed in Ireland in 1689, but after the defeat of the Jacobite forces by the Williamite forces at the Battle of the Boyne in July 1690, James returned to France.
Split into simpler sentences: James made one serious attempt to recover his crowns from William and Mary when he landed in Ireland in 1689. After the defeat of the Jacobite forces by the Williamites at the Boyne, James returned to France.