Union Col. (later General) John McNeil pursued Porter, who planned an ambush with perhaps 125 men according to participant Mudd (though Federal estimates of Porter's strength ran from 400 to 600 men). The battle is called "Vassar Hill" in the History of Scotland County; Porter himself called it "Oak Ridge," and Federal forces called it "Pierce's Mill," after a location 1.5 miles northwest of the battlefield. A detachment of three companies (C, H, I), about 300 men of Merrill's Horse, under Major John Y. Clopper, was dispatched by McNeil from Newark against Porter, and attacked him at 2 p.m. on Friday, July 18, on the south fork of the Middle Fabius River, ten miles southwest of Memphis. Porter's men were concealed in brush and stayed low when the Federals stopped to fire prior to each charge. Porter's men held their fire until the range was very short, increasing the lethality of the volley. Clopper was in the Federal front, and out of 21 men of his advance guard, all but one were killed and wounded. The Federals made at least seven mounted charges according to Mudd, doing little but adding to the body count. A battalion of roughly 100 men of the 11th Missouri State Militia Cavalry under Major Rogers arrived and dismounted. While Clopper claimed to have driven the enemy from the field after this, Mudd indicates that the Federals instead fell back and ended the engagement leaving Porter in possession of the field until he withdrew. Clopper's reputation suffered as a result of his poor tactics. Before the final charge one company officer angrily asked, "Why don't you dismount those men and stop murdering them?"