Texas declared its secession from the Union on February 1, 1861, and joined the Confederate States on March 2, 1861, after it had replaced its governor, Sam Houston, who had refused to take an oath of allegiance to the Confederacy. As with those of other states, the Declaration of Secession was not recognized by the US government at Washington, DC. Some Texan military units fought in the Civil War east of the Mississippi River, but Texas was more useful for supplying soldiers and horses for the Confederate Army. Texas' supply role lasted until mid-1863, when Union gunboats started to control the Mississippi River, which prevented large transfers of men, horses, or cattle. Some cotton was sold in Mexico, but most of the crop became useless because of the Union's naval blockade of Galveston, Houston, and other ports.
Secession
In the early winter of 1860, Texan counties sent delegates to a special convention to debate the merits of secession. The convention adopted an "Ordinance of Secession" by a vote of 166 to 8, which was ratified by a popular referendum on February 23.
From the Ordinance of Secession, which was considered a legal document, Texas also issued a declaration of causes spelling out the rationale for declaring secession. The document specifies several reasons for secession, including its solidarity with its "sister slave-holding States," the U.S. government's inability to prevent Indian attacks, slave-stealing raids, and other border-crossing acts of banditry. It accuses northern politicians and abolitionists of committing a variety of outrages upon Texans. The bulk of the document offers justifications for slavery saying that remaining a part of the United States would jeopardize the security of the two. The declaration includes this extract praising slavery, in which the Union itself is referred to as the "confederacy":
At this time, African Americans comprised around 30 percent of the state's population, and they were overwhelmingly enslaved. According to one Texan, keeping them enslaved was the primary goal of the state in joining the Confederacy:
Secession convention and the Confederacy
Following the election of Abraham Lincoln in 1860, public opinion among free citizens in the cotton states of the Lower South (South Carolina through Texas) swung in favor of secession. By February 1861, the other six states of the sub-region had separately passed ordinances of secession. However, events in Texas were delayed, largely due to the resistance of Southern Unionist governor, Sam Houston. Unlike the other "cotton states"' chief executives, who took the initiative in secessionist efforts, Houston refused to call the Texas Legislature into special session to consider the question, relenting only when it became apparent citizens were prepared to act without him.
In early December 1860, before South Carolina even seceded, a group of State officials published via newspaper a call for a statewide election of convention delegates on January 8, 1861. This election was highly irregular, even for the standards of the day. It often relied on voice vote at public meetings, although "viva voce" (voice) voting for popular elections had been used since at least March 1846, less than three months after statehood. Unionists were often discouraged from attending or chose not to participate. This resulted in lopsided representation of secessionists delegates.
The election call had stipulated for the delegates to assemble in convention on January 28. Houston called the Legislature into session, hoping that the elected body would declare the unauthorized convention illegal. Though he expressed reservations about the election of Abraham Lincoln, he urged the State of Texas to reject secession, citing the horrors of war and a probable defeat of the South. The convention removed Houston from the governorship, then promoted the Lieutenant Governor, Edward Clark.
With gubernatorial forces routed, the Secession Convention convened on January 28 and, in the first order of business, voted to back the legislature 140–28 in that an ordinance of secession, if adopted, be submitted for statewide consideration. The following day, convention president Oran Milo Roberts introduced a resolution suggesting Texas leave the Union. The ordinance was read on the floor the next day, citing the failures of the federal government to protect the lives and property of Texas citizens and accusing the Northern states of using the same as a weapon to "strike down the interests and prosperity" of the Southern people.