By September 24, Price's column had reached
Fredericktown, where he learned that the town of
Pilot Knob and the
St. Louis & Iron Mountain Railroad were held by Union forces under the command of Brigadier General
Thomas Ewing Jr. Price had no interest in allowing an enemy force to operate in the rear of his army while he advanced to
St. Louis, so he sent Marmaduke and Fagan's divisions to Pilot Knob; Shelby and his men operated north of the town. On September 26, Ewing's command fought off Fagan's division at
Arcadia before withdrawing to the defenses of
Fort Davidson. The next day, Price moved against the fort and offered Ewing surrender terms; the latter refused, as he was afraid of being executed for his unpopular
issuance of General Order No. 11 the previous year. Holding out, the Union defenders repulsed multiple assaults, before slipping out of the fort at 03:00 on September 28. The Confederates suffered at least 800 casualties during the engagement and their morale decreased, leading Price to abandon the attempt against St. Louis. After abandoning the St. Louis thrust, Price's army headed for
Jefferson City, although the Confederates were slowed by bringing along a large
supply train. On October 7, the Confederates approached Jefferson City, which was held by about 7,000 men mostly inexperienced militia commanded by Brigadier General
Egbert Brown. Faulty Confederate intelligence placed the Union strength at 15,000, and Price, fearing another defeat like Pilot Knob, decided not to attack the city, and began moving his army toward
Boonville the next day. Boonville was in the pro-Confederate region of
Little Dixie, and Price was able to recruit new soldiers. Estimates of the number of new recruits vary between writers: the historian Charles D. Collins states 1,200 men; Christopher Phillips, writing for the
Kansas City Public Library, provides 2,000 men; and the historian Kyle Sinisi states that a minimum of 2,500 men joined the Confederates in the region. Price, needing weapons, authorized two raids away from his main body of troops: Brigadier General
John B. Clark Jr. and 1,800 men were sent to
Glasgow, and Brigadier General
M. Jeff Thompson led
Shelby's Iron Brigade to
Sedalia. Both raids were successful. Price's army next fought a series of engagements as it moved westwards towards
Kansas City, Missouri, culminating in the
Battle of Westport on October 23. At Westport, the Confederates were soundly defeated by the commands of Major Generals
James G. Blunt and
Alfred Pleasonton. Shelby's men provided the Confederates with a
rearguard, and the Army of Missouri retreated southwards. The Confederates still had a large supply train with them, slowing the retreat. By the evening of October 24, the Army of Missouri had entered
Kansas; Confederate soldiers
looted and burned as they went. That night, Price camped near
Trading Post in
Linn County, with the camp split into two segments by the
Marais des Cygnes River. Price believed that the Union pursuers would attempt to swing around his
flank and block his path of retreat and was not expecting a significant Union force to attack the Trading Post position. Meanwhile, the Union pursuers were at West Point, Missouri. Blunt suggested an ambitious flanking movement, but was overruled by Major General
Samuel R. Curtis, commander of the
Department of Kansas. The plan would have involved only using a token force to attack the Confederate position at the Marais des Cygnes and slipping most of the rest of the Union army around the Confederate flank to attack Price's army in the morning. Both the flanking movement and crossing a river at night posed risks, and Blunt's plan did not consider the fact that the terrain south of the Marais des Cygnes was not conducive to rapid movement. It also assumed that the Confederates would remain stationary. Instead, Curtis ordered Pleasonton to make a
frontal attack against Price. Pleasonton, who was heavily fatigued, gave temporary control of his division to Brigadier General
John B. Sanborn. Sanborn moved against Price with a cavalry force at Trading Post late on the night of the 24th. His line, which consisted of the
4th Iowa Cavalry Regiment and three
companies of the
2nd Colorado Cavalry Regiment on the right and the
6th and
8th Missouri State Militia Cavalry Regiments on the left, made contact with Fagan's Confederates, who were now serving as the Confederate rearguard. A brief
friendly fire incident involving the 4th Iowa Cavalry and the 2nd Colorado Cavalry ensued due to the Iowans being unaware of the presence of the Colorado unit in their front, as well as some light skirmishing with Fagan's forces. Sanborn was unsure of the Confederates' strength, but thought it might be as many as 10,000 men. With his men fatigued and operating in a
thunderstorm, he withdrew most of his line, except for the 6th Missouri State Militia Cavalry, which continued skirmishing throughout the night. Fagan informed Price of the action, and the Confederates began retreating about midnight. ==Battle==