Flaget journeyed west in a wagon headed through the Allegheny Mountains to Fort Pitt, the area now known as Pittsburgh, Pennsylvania. A letter of introduction from Bishop Carroll provided an introduction to General "Mad" Anthony Wayne. Travel was to be by flatboat down the Ohio River, but due to low water conditions he stayed at Fort Pitt for a few months. While there he learned English and tended to those afflicted by an outbreak of smallpox in the area. Flaget left Pittsburgh in November and traveled down the Ohio River to the Falls of the Ohio (Louisville), where he continued on his journey to Fort Vincennes with George Rogers Clark. They reached the fort on December 21, 1792.