This is the story of the Spanish Royal Commissioner Francisco de Saavedra who, based in Havana, played an indispensable role in uniting French and Spanish forces during the late stages of the American Revolutionary War. He united the armies and navies of both countries and this led to the Spanish victory over the British at the Battle of Pensacola in May 1781, and later at the American victory over the British at the Battle of Yorktown in October 1781. Yorktown was the decisive American victory that led the British to abandon their attempt to defeat the rebels in North America. Saavedra provided the finance for Yorktown that allowed a French fleet under Lt. General de Grasse to urgently sail with men, artillery and the money that turned the tables by trapping the British army at Yorktown while generals Washington and Rochambeau marched down from New York to Virginia with their combined armies. Once united they delivered a crushing defeat to the British. Saavedra, until now, has not been credited for his part in this story. He wrote a diary which has been used to add colour to other peoples accounts of the war. Through much research in French and Spanish archives I have found how highly valued he was by the French foreign minister and court and also by the Spanish court who sent him on his mission. I have used a lot of direct quotes that bring his mission alive.