In the late summer of 1864, Grant and Lee were locked in a stalemate at Petersburg. Sherman had laid siege to Atlanta. Sheridan was marauding the Shenadoah Valley. Most of the Union forces from Missouri were assigned to the eastern theater. Jefferson Davis had ordered E. Kirby Smith, Commander of the Trans-Mississippi Department, to send his infantry across the Mississippi River to reenforce the outnumbered armies of the Confederate commanders in the east.
        Smith, reluctant to give up his armies, informed Davis he needed his men to liberate Missouri. He said he had grand plans to take St. Louis and the capital at Jefferson City, and even reinstate Missouri's Confederate Governor-in-exile, Thomas C. Reynolds. This action would swell the ranks of the Confederate Army with tens of thousands of volunteers while drawing Union troops from the east, taking the pressure off Lee, Hood and the other Confederate generals fighting there. Also, it was hoped anti-war sentiment in the north would lead to Lincoln's defeat in the coming November election, forcing the Union to sue for Peace with Separation.
        Davis relented to Kirby's plans, but Kirby never sent his infantry to Missouri, instead opting to send a great cavalry force on the expedition. This "Army of Missouri" was to be led by Major General Sterling Price, former Governor of Missouri. A popular general, known by his men as "Old Pap", Price was a much better politician than a general.
        Price's 12,000 man army was composed of three divisions with 14 artillery pieces led by Major General James F. Fagan, Major General John S. Marmaduke and Brigadier General Joseph O. Shelby. After eluding Major General Frederick Steele's forces in northeast Arkansas, Price set forth from Pocahontas, Arkansas on September 19. However, "Old Pap's" army was poorly armed and ill equipped. Many of his men didn't even have weapons and some 1,000 had no horses, slowing his advance.
        Between the Army of Missouri and St. Louis lay Fort Davidson at the town of Pilot Knob in Arcadia Valley, the southern terminus of the Iron Mountain Railroad. By September 23 Price had arrived at Fredericktown, 90 miles south of St. Louis and 20 miles east of Fort Davidson. There, Price received word that 8,000 Union troops were encamped near St. Louis, but a small force of 1500, commanded by the despised Brigadier General Thomas Ewing, Jr., garrisoned Fort Davidson.
        Instead of moving rapidly north, Price, seeing an opportunity for an easy victory, sent Fagan and Marmaduke west to Pilot Knob while ordering Shelby north to destroy railway bridges and sever communications between St. Louis and Arcadia Valley. Shelby was to then turn south in support of the assault on Fort Davidson. General Shelby spoke against the plan:

"I favored moving rapidly into St. Louis and seizing it.... I then and there...stated what the result would be if we attacked Pilot Knob. I could see nothing as an inducement; they had nothing we required. It would only cripple and retard our movements, and I knew too well that good infantry, well entrenched, would give us Hell, and Hell we did get...."

        Major General William S. Rosecrans commanded the Department of Missouri for the Federals. Ewing was in command of the Federal District of St. Louis and actually did not arrive at Fort Davidson and take command until September 26. Major James Wilson was in command at Pilot knob until the arrival of Ewing.
        Rosecrans did not believe reports that Price was in southeast Missouri with an army. Also, Rosecrans had but 10,000 or so men spread throughout the state, defending against relentless guerilla raids. Grant did not hold Rosecrans in high regard and had given Major General A.J. Smith, on his way to Sherman with a 6,000 man detachment of the XVI Army Corps, descretion to divert if he was needed to reenforce Rosecrans against an invasion. Smith had arrived at Jefferson Barracks, south of St. Louis, on September 17.
        September 26 found about 1447 soldiers and volunteer citizens at Pilot Knob from the following commands: the 14th Iowa Infantry (142), the 47th Missouri Infantry (500), Company F of the 50th Missouri Infantry (80), Battery H of the 2nd Missouri Light Artillery (134--6 guns), the 3rd Missouri State Militia Cavalry (347), Company L of the 2nd Missouri State Militia Cavalry (44), Company G of the 1st Missouri State Militia Infantry, (serving as artillery, 58--7 guns) plus a number of white and black civilian volunteers.
        For the Confederates, Fagan's Division (1,775) was composed of Cabell's Brigade of 8 Arkansas Cavalries with a battery of 2 guns, Slemon's Brigade (459) of 4 Arkansas Cavalries, Dobbin's Brigade (835) of 3 Arkansas Cavalries and a battery of 2 guns, McCray's Brigade (1,700) of 2 Arkansas mounted infantries and the 15th Missouri Cavalry, and 3 unattached Arkansas Cavalries totaling 300 men.
        Marmaduke's Division (3756) was composed of Clark's Brigade (2,200) of 7 Missouri Cavalries, 2 batteries of 3 guns each and an engineer company, Freeman's Brigade (1,356) of 2 Arkansas and 1 Missouri Cavalries, and Slayback's Detachment (200) of Missouri Cavalry.
        Fort Davidson itself is a hexagonal earthenwork surrounded by a dry moat. It was connected by two rifle pits extending north (190 yards) and south (150 yards) accessed by sally ports (tunnels). The fort had a drawbridge and sat in a valley between the moutains Pilot Knob (east) and Shepherd (south). It contained the following impressive concentration of artillery: four 32 pound siege guns, three 24 pound howitzers and six 3-inch ordnance rifles. In the center of the fort was a buried powder magazine.