After months of reverses, the Union army was going on the offensive in the spring of 1862 as General McClellan prepared for his Peninsula Campaign.

In Tennessee, General Grant had just captured Ft. Henry and Ft. Donelson; and in southwestern Missouri, Gen. Samuel R. Curtis had driven Sterling Price and his Missouri State Guard out of the state and into the arms of General Ben McCulloch's Confederate army in northwestern Arkansas. Using the united armies of Price and McCulloch, the new Confederate department commander, Earl Van Dorn, struck back at Curtis' Federal army which was now outnumbered and two hundred miles from its supply base. For two days in early March 1862, the armies of Van Dorn and Curtis fought in the wilds of the Ozark Mountains at a place called Pea Ridge. Control of northern Arkansas and southern Missouri for the rest of the war hung on the outcome.