Price sent recruiters ahead of him with the intention of adding these recruits to his force in his sweep across Missouri. Thornton was one of Price's recruiters. He marched into Platte City on July 10 with no opposition. After recruiting, looting, and enjoying Platte City for two days, Thornton and his men headed for Camden Point and encamped. The townspeople welcomed them and prepared the picnic on July 13.
Contemporary sources locate the picnic grounds in a bluegrass pasture north of town.
Relics of bullets, cannon balls, and accouterments have been found in the northern part of Camden Point through the years. J.H. Ford's combined troops from St. Joseph, Liberty, Fort Leavenworth, and Weston dashed up the lane south of town firing at Thornton's fleeing pickets. Thornton dropped the flag and ran away at the first shots. The flag was captured and is today in the possession of the Colorado Historical Society. Thornton was not the only person there to panic.