Complex sentence: Unluckily, Captain Holford's ship met with this ship at sea, and the captain of Vane's ship invited Holford, a friend of his, to dine with him.
Split into simpler sentences: Unluckily, Captain Holford's ship met with this ship at sea. The captain of Vane's ship was a friend of Holford's, and he invited Holford to dine with him.