The incident occurred on the return journey, just off the Missouri River in what is today northwestern North Dakota. Lewis and the expedition’s other leader, William Clark, had split up, each taking a part of their men on different paths so that even more of the lands recently brought into the country through the Louisiana Purchase could be explored. On August 11, 1806, as Lewis and his group traveled down the Missouri, they stopped to go onshore and hunt for elk they had seen. Lewis took one of his men, a Private Cruzatte, for the effort. The men became separated, and as Lewis raised his rifle to his shoulder for a shot, he himself was hit by a rifle bullet that entered his left butt cheek “an inch below his hip joint” and exited through his right butt cheek, “leaving a three-inch gash the width of the ball,” wrote Stephen E. Ambrose in his 1996 book Undaunted Courage: Meriwether Lewis, Thomas Jefferson, and the Opening of the American West.
Lewis called out to Cruzatte, but got no answer. Fearing an Indian attack, the severely wounded Lewis somehow made his way back to his other men on the river. He tried to lead them back to site of the shooting to save Cruzatte, but his injury became too painful and debilitating, so he told his men to leave him behind. Lewis struggled back to the boats on the river and armed himself, later writing that he “determined to sell my life as deerly as possible.” After about 20 minutes, the men returned with Cruzatte, who seemed oblivious to what had happened, and said he had not heard Lewis call out to him after he had been shot. Cruzatte denied being the culprit. But the bullet, which had lodged in Lewis’s leather breeches, was from the same type of late-model U.S. Army rifle carried by Cruzatte, which was not a weapon likely to be in the hands of a hostile Indian.
Lewis himself was the closest thing to a doctor on the expedition, although he had little training in the field – only a two-week tutelage under one of America’s leading medical experts, Dr. Benjamin Rush, as in preparation for the expedition. So Lewis dressed his wound himself, placing roles of lint into the holes in his butt. He was forced to lie on his stomach and the boats continued down the river. The pain became so great that he couldn’t be moved, so he spent the night, after the group made camp on the shore of the river, on his stomach in one of the boats. He became feverish, but the application of a poultice of Peruvian bark, seemed to control that, but not the pain.
Lewis’ group rejoined Clark’s group the next day. Lewis was still on his belly, and fainted with pain when Clark changed the dressings on the wounds. Over the next days, the wounds appeared to be healing, but still Lewis couldn’t walk. Improvement was again noted on August 22, when Clark wrote that Lewis “walked a little to day for the first time. I have discontinued the [lint] in the hole the ball came out.” And the next day, Clark wrote that Lewis “is recovering fast the hole in his thy where the Ball passed out is Closed and appears to be nearly well. The one where the ball entered discharges very well.”
There were setbacks in Lewis’ recovery, though. Clark reported a few days later that Lewis“hurt himself very much by takeing a longer walk ... than he had Strength to undergo, which Caused him to remain very unwell all night.” The next morning, Clark wrote that Lewis“had a bad nights rest and is not very well this morning.” But by the time the expedition returned to St. Louis about a month later, in late September 1806, Lewis seems to have fully recovered.