Union armies at the battles of Wilson's Creek and Lexington in 1861, but by the end of the year, Price and the MSG were restricted to the southwestern portion of the state due to the arrival of Union reinforcements. Meanwhile, Jackson and a portion of the state legislature voted to secede and join the Confederate States of America, while another element voted to reject secession, essentially giving the state two governments. In March 1862, a Confederate defeat at the Battle of Pea Ridge in Arkansas gave the Union control of Missouri. For the rest of the year, and through 1863, Confederate activity in the state was largely restricted to guerrilla warfare and raids. By the beginning of September 1864, events in the eastern United States, especially the Confederate defeat in the Atlanta campaign, gave incumbent president Abraham Lincoln, who supported continuing the war, an edge in the 1864 United States presidential election over George B. McClellan, who promoted ending the war. At this point, the Confederacy had very little chance of winning the war. Meanwhile, in the Trans-Mississippi Theater, the Confederates had defeated Union attackers in the Red River campaign in Louisiana in March through May. As events east of the Mississippi River turned against the Confederates, General Edmund Kirby Smith, commander of the Confederate Trans-Mississippi Department, was ordered to transfer the infantry under his command to the fighting in the Eastern and Western Theaters. This proved to be impossible, as the Union Navy controlled the Mississippi River, preventing a large-scale crossing. Despite having limited resources for an offensive, Smith decided that an attack designed to divert Union troops from the principal theaters of combat would have the same effect as the proposed transfer of troops. Price and the new Confederate Governor of Missouri Thomas Caute Reynolds suggested that an invasion of Missouri would be an effective offensive; Smith approved the plan and appointed Price to command the campaign. Many of the Union troops previously defending Missouri had been transferred out of the state, leaving the Missouri State Militia as the state's primary defensive force. Price expected that the offensive would create a popular uprising against Union control of Missouri, divert Union troops away from principal theaters of combat, and aid McClellan's chance of defeating Lincoln. Price's column entered the state on September 19. This force was formally known as the Army of Missouri and contained three divisions, which were