You'll find the link below.
As you know the Federals defeated Price at Pea Ridge in March 1862. This secured Missouri for the Union. Union attempts to conquer Arkansas in 1862 were thwarted by Thomas Hindman who did a magnificent job of raising an army to oppose the invading Federals. However Blunt and Herron beat Hindman at Prairie Grove and in 1863 the Federals took advantage of this defeat to seize Fort Smith, Little Rock and the northern half of the state.
In March 1864 the Federals were ready to administer the knock-out blow and conquer all of Arkansas and Texas. Two Union armies converged on Shreveport in what's known as the Red River Campaign. Both armies were defeated.
Grant withdrew many of the Union soldiers from the Trans-Mississippi and suddenly as though by a miracle the Federals in Arkansas were on the defensive, holding a few posts along the Arkansas and White Rivers.
During June-August 1864 Shelby recruited 6,000 men for Price and gave many of them battle experience by attacking the beleaguered Federal posts. Price persuaded E. Kirby Smith to allow him to invade Missouri with 12,000 cavalry.
Smith had to keep the Federals from harrassing Price and keep the way open for his return. So he sent Magruder to menace Little Rock and he sent Gano and Waitie to raid Fort Smith and the Indian Territory.
Many people feel that Smith would have been wiser to capture the posts along the White and Arkansas River with Magruder's and Price's forces. The invasion of Missouri was simply too risky.
Steele tried to catch up with Price just as he started his raid by sending Winslow's cavalry and Mower's infantry but they were unsuccessful. He should probably have sent them to Cape Girardeau instead to help defend the state against Price.
Here's the link.