Original sentence: In one scene, Charles visits his mistress, in her apartments in White Hall palace, Lady Castlemain, only to find her in bed with a young John Churchill, future Duke of Marlborough, who would become one of Englands most famous military commanders and play a important part in the War of the Spanish Succession
Edited sentence: In one scene, Charles visits his mistress, in her apartments in White Hall palace, Lady Castlemain, only to find her in bed with a young John Churchill, future Duke of Marlborough, a brilliant general under William III and Anne, who would rehearse the Duke of Wellington's crushing defeat of French continental ambitions