The Battle of Westport was the culmination of a more or less continuous series of battles that began on October 19, 1864 in Lexington, Missouri. Major General Sterling Price had invaded Missouri with the Confederate Army of Missouri in order to capture war supplies and recruit supporters of the Confederacy. Heading west towards Kansas City, Price's army was being pursued by three Union cavalry divisions under the command of Major General Alfred Pleasonton. Waiting for Price in Kansas City was the Union Army of the Border commanded by Major General Samuel R. Curtis. Outnumbered by the advancing Confederates, Curtis' immediate objective was to delay Price long enough to allow Pleasonton time to catch up. While Curtis established his main line of defense just east of Kansas City along the Big Blue River, He sent Major General James G. Blunt east with two cavalry brigades to delay Price's advance.
The initial engagement began on the morning of October 19, 1864 on the outskirts of Lexington, Missouri. The Union troops fought a delaying action as they withdrew to the Little Blue River. Here Blunt set up another defensive line in order to delay the Confederate advance. The Confederate commanders attacked on the morning of October 21, 1864. After holding off the Confederate attackers for most of the morning, the Union defenders withdrew to Independence, Missouri. The Confederates continued to press their advantage in numbers and took the attack into Independence. Again the Union forces resisted but soon fell back to Curtis' main line of defense along the Big Blue River.
It was cold and windy on the morning of Saturday, October 22, 1864 when Price sent the cavalry divisions of Brigadier General Jo Shelby and Major General James F. Fagan to force a crossing of the Big Blue River. He sent his massive wagon train of supplies (600 wagons and 3,000 cattle) southwest towards Little Santa Fe guarded by Cabell's Brigade from Fagan's Division. Shelby was able to discover and then exploit a weakness in the Union defensive line. The Confederates were able to get across the Big Blue and outflank the Union defenders. Curtis realized that his Union army was in great danger and quickly withdrew from the Big Blue River to Westport.
On this same day, Pleasonton had finally caught up to the rear of Price's army in Independence. Price assigned Major General John S. Marmaduke's Division the job of holding back Pleasonton. Marmaduke was able to hold off Pleasonton long enough for Price's wagon train to get on its way to Little Santa Fe. Marmaduke's Division set up a defensive line on the west side of the Big Blue River at Byram's Ford. Shelby and Fagan occupied the heights just south of Brush Creek and prepared to attack the Union positions on the morning of Sunday, October 23, 1864.
At midnight, Curtis met with his staff in the Gillis House. Curtis needed a plan for the morning. Around 2:00 A.M. Curtis had decided to stand and fight at Westport. At 3:00 A.M. he sent out orders for the Army of the Border to concentrate along the north side of Brush Creek. Colonel Charles R. Jennison's First Brigade was ordered to move to Brush Creek. Colonel Thomas Moonlight's Second Brigade was ordered to move to the state line south of Brush Creek. Colonel James Hobart Ford's Fourth Brigade was ordered t move to Brush Creek. Colonel Charles W. Blair's Third Brigade was moved south to support the First and Fourth Brigades. Major General George W. Dietzler was ordered to bring his Kansas Militia into Westport. Blunt was to attack at dawn. In coordination with Curtis, Union General Pleasonton was also going to attack at Byram's Ford on daybreak on October 23rd.