Fort Washington was built between September 1789 and January of 1790, at the site of modern day Cincinnati, to protect the settlers living in southwestern Ohio. It was said to be one of the most solid substantial wooden fortresses of any in the Western Territory. The stockade wall was two stories high with a block house at each of its four corners. Because of the importance of the fort it was named after President George Washington.
While at Fort Washington Harrison met and married Anna Tuthill Symmes (November 25, 1795) without her father's approval. She was the daughter of John C. Symmes, a judge and wealthy land investor.