Francois Joseph Paul de Grasse was an admiral in the French navy, and is probably best known for his victory in the Battle of the Chesapeake, where he prevented British troops from arriving to reinforce the army at Yorktown.
De Grasse was the youngest child of a French nobleman. He joined the military at the age of 11 when he became a page with the religious/military Order of Malta. He joined the French Navy proper in 1740. By 1775 he was serving as a Captain, he helped secure Saint Domingue (now Haiti) for the French - which probably looked good on a resume at the time.
De Grasse was promoted to Admiral in 1781 and despite failing health was given orders to sail for America to help Washington. His victory at Chesapeake was so significant that Washington wrote to him the day after Cornwallis surrendered at Yorktown saying the honour of the victory belonged to De Grasse.
De Grasse died in 1788, just before the beginning of the French Revolution. Despite his role aiding rebels in America, De Grasse was considered nobility in France and his estate was ransacked by French revolutionaries. His family fled to the United States, where they were welcomed as the children of a hero.
I guess 'hero' and 'oppressor' all depend on your perspective. You say tomato, I say tom-ahto... you say potato, I say pot-ahto.
Actually, no one says potahto.