In January General Samuel Curtis formed the Army of the Southwest in Rolla, and launched a winter campaign to push Gen. Price's command from southwest Missouri. By mid-February the Federals forced the Southerners into the Boston Mountains of Arkansas. The Confederates struck back and surprised the Federals at the battle of Pea Ridge, Arkansas on March 7 and 8. The Federals rallied and drove the Southerners into a disastrous retreat. Although fought in Arkansas, this victory kept Missouri in the Union the remainder of the war.
General Curtis' victory at Pea Ridge did not end hostilities within the state. There was fighting and a siege at Island Number 10 in the Mississippi River and New Madrid (February 28-April 8) in southeast Missouri. General John Pope and the Union navy achieved the victory over Confederate General John P. McCowan.
Numerous skirmishes marked the period from March to late summer in the state. There were a series of small forays into the central portion of the state to recruit men and obtain horses. On August 15-16 there were clashes at Lone Jack. The Confederates, led by Col. John T. Coffee, attacked an 800-man Federal force and following a series of attacks and counter-attacks drove the Union men back to Lexington. As was usually the scenario, the Confederates were unable to hold their ground when threatened with a much larger army. They hastily withdrew to the counties along the Missouri-Arkansas border when pressed by Union forces.
With the increased Southern activity in the border region Federal troops were sent to investigate in mid-September. The two sides clashed at Newtonia, an important crossroads town, on September 30. After early Union success, Confederate reinforcements arrived, and with the aid of their artillery, routed the Federals. Once again, the Southerners failed to hold the area with the arrival of Union reinforcements. The fighting at Newtonia opened the campaigning that would eventually lead to the decisive struggle at Prairie Grove, Arkansas on December 7. The Federal victory in Arkansas quieted Rebel activities in Missouri for a brief time.
In October an important psychological and historical moment occurred when African Americans, mustered into military service as the 1st Kansas Colored Infantry, engaged in their first combat action. The skirmish at Island Mound, while not a crucial military action, answered a key question to many political and military leaders about the African Americans fighting qualities.