In the spring of 1866, William Thomas, his eight-year-old son Charley, and Joseph Schultz left southern Illinois for southwest Montana. Traveling by prairie schooner drawn by mules, they joined a wagon train at Fort Laramie, Wyoming, and started up the Bozeman Trail bound for the Gallatin Valley. After the wagon train safely passed through hunting grounds defended by Lakota and Northern Cheyenne warriors, it stopped to rest and make repairs at the Big Horn River crossing just north of the Montana-Wyoming border. Believing the trail west of the Bighorn River to the Gallatin Valley was safe from Indians, the three men left the security of the large wagon train and traveled on alone. A few days later, on August 24, 1866, Indians attacked their camp near the bank of the Yellowstone. William and Charley Thomas were killed near their wagon, and Schultz was killed by the river where he was fishing. The wagon train they had left reached the site later that day, and the three were buried in a common grave beside the road. The scant details that later returned deeply impressed William Thomas's seven-year-old nephew, who seventy-one years later, in 1937, closely followed the Bozeman Trail by car and located the forgotten gravesite.