 The fleet landed a 7,000-man invasion force of Royal Marines, German mercenaries, and black militia troops from the island of Tobago, commanded by General Sir Ralph Abercromby (also spelled "Abercrombie").However, the resolute Spanish defense forced the British to withdraw after two weeks.At daybreak on 10 August, "Arethusa", commanded by Captain Thomas Wolley, was in the Atlantic Ocean at when she sighted three ships to windward.