Near here, as Upton set up his four-cannon battery, Lieutenant John V. Dubois saw movement across the creek. On the Union left, four companies of regulars drove the enemy across a cornfield to timber beyond, but were then driven back in turn. Dubois turned his guns on the attackers, and a few rounds of spherical case defeated them with some loss. As Union troops retreated at a slow walk while firing and the enemy advanced its reserves, the day seemed lost until Dubois's battery struck their exposed flank. The small force rallied for one more effort for the old flag and drove them back with great slaughter, leaving the ground black with their dead before a lull came from sheer exhaustion. During the rest of the day, Dubois's battery blasted several Southern threats and covered the Union retreat from the battlefield. An 1851 graduate of West Point, Lieutenant John V. DuBois had been assigned to the Regiment of Mounted Riflemen on the western frontier. In early June 1861, while passing through Fort Leavenworth, Kansas, escorting 255 replacements for the regiment, he and two other officers were taken by Major Samuel Sturgis, along with the recruits, to form two infantry companies and an artillery battery. Within two weeks, Dubois and his new battery marched with Sturgis to join Lyon in Missouri.