Although only about 22,000 Texas families, approximately one in four, owned slaves, and most slave-holders lived in the eastern part of the state, most Texans believed that slavery was vital for continued prosperity. The election of President Abraham Lincoln in November 1860 alarmed them. In a June 1858 speech Lincoln had stated, "A house divided against itself cannot stand. I believe this government cannot endure permanently half slave and half free. I do not expect the Union to be dissolved. I do not expect the house to fall, but I do expect it will cease to be divided."
At a state convention held in Austin in early 1861, delegates voted 166 to 8 to secede from the Union. (Some 70 percent of the delegates owned slaves.) Texans overwhelmingly approved the ordinance of secession, and in late March, Texas joined the Confederacy. Since pro-union Governor Sam Houston refused to take the oath of allegiance to the new government, the office of governor was declared vacant. Lieutenant Governor Edward Clark, who supported the Confederacy, became governor. Confederate troops soon opened fire on South Carolina's Fort Sumter. In response, President Lincoln called for 75,000 Union soldiers to face the rebellion. The Civil War had begun.
During the next four years, approximately 90,000 Texas men participated in the war. After the loss of more than 600,000 soldiers (approximately 275,000 Confederates and 325,000 Union men) and the destruction of much of the South, the Confederacy surrendered in the spring of 1865. Union General Gordon Granger arrived in Galveston on June 19. He declared that the war was over and that Lincoln's Emancipation Proclamation was in effect. All slaves were free. This date is now commemorated as Juneteenth, an official Texas holiday.