 Fleming served as a surgeon under Major Andrew Lewis, and experienced many attacks by the Shawnee, as well as severe clothing and food supply problems during what became known as the "Sandy Creek Voyage," because they reached the headwaters of the Clinch River and the streams that form the Big Sandy River.Weathering problems in accessing his promised bonus for serving as the unit's surgeon, Fleming received a promotion to Second Lieutenant the following spring, although Capt.Hog was demoted after complaints at Fort Vaux.