Arkansas seceded from the Union on May 6, 1861, becoming the 9th state to join the Confederacy during the American Civil War. The decision to secede followed the election of Abraham Lincoln as president, which led to increasing tensions between the Northern and Southern states over issues such as slavery and states' rights.

The Arkansas Secession Convention voted to secede, with a majority of delegates supporting the decision, despite some internal divisions in the state. While many in the state were opposed to secession, especially in the northern part of Arkansas, the state ultimately joined the Confederate cause. 

After Arkansas seceded, it became a strategic part of the Confederacy, with battles like the Battle of Pea Ridge (1862) and the Battle of Prairie Grove (1862) taking place within its borders. Arkansas remained a Confederate stronghold throughout most of the war but faced significant challenges, including internal resistance and the Union's efforts to gain control of the state. In 1863, the Union took control of the state capital, Little Rock, and Arkansas was eventually readmitted to the Union on June 22, 1868, after the war ended.