Yes, Sam was against secession, and yes, his stance on slavery overall is more nuanced than I suggested. He was against its westward expension on practical grounds. And he thought emancipation would result in a calamity.
Houston initially had the support of many of his constituents in Texas. As more slaveholders moved into the state,[18] he suffered politically for holding firm to his belief that every state should decide for itself whether it wanted to be a slave state. The only Southern Democrat to vote against the act, the Texas legislature did not reappoint him to the Senate, but allowed him to finish out his term until March 4, 1859.[2] It later earned him a spot, though, in John F. Kennedy's Profiles in Courage.[19] Houston said of his stance: "The glory of my life was that I had the moral manhood on that occasion to stand up against the influences which surrounded me, and to be honest in the worst of times."[20] Houston lost the 1857 Texas gubernatorial election against Hardin Richard Runnels, but defeated Runnels in the 1859 election, becoming the 7th Governor of Texas.[2]
Speech on slavery (1855)[edit]
Houston gave a speech on slavery on February 22, 1855, in Boston in which he stated that each of the original states relied on slave labor, although Northern states later outlawed slavery. He felt that each state should determine whether to allow slavery or not.[21]
Houston stated that progress in the United States was due to the supply of low-cost foreign labor, and if low-cost foreign labor could be sustained without the capital investment to purchase black people, slavery would die. He expressed his belief that blacks were better suited to performing long hours of hard work in hot weather in a way that white people could not sustain. Throughout his speech, Houston talked of the need for Northern and Southern states to work together for their individual and mutual interests.[22] The products of slave labor, sugar, and cotton were purchased by Northern states so that there was a mutual dependence on slavery.[21]
He felt that if enslaved people were to be freed altogether, they would end up living on the streets without jobs, without means to sustain themselves, and the Southern economy would be ruined.[23]
He expressed his opinion about a possible future for enslaved people in the Colony of Liberia:
I think that "insufficiently pro-slavery" better describes Houston's public pronouncements on slavery than "nuanced."
In the slave states, from the 1830s onward, you could not be anti-slavery and hold office. At times, you couldn't be anti-slavery and hold on to your life. Southern abolitionists like the Grimke sisters had to move to the north to avoid being lynched.
You could be opposed to the expansion of slavery and not be lynched, but after the issue of further westward expansion of slavery became an issue, during and after the Mexican War, that was a losing position for a southern politician to hold.
And you could be a "Unionist," opposed to secession, as Houston was, and not be lynched. There were men who voted to preserve the Union in every secession convention.
In societies or organizations where only one point of view is allowed, it's not enough to just not oppose that one viewpoint. The competition is not between that viewpoint and an opposing one, but who can most ardently advocate the one allowable viewpoint.
You can most easily see it at work in authoritarian/totalitarian governments, where all aspiring politicians try to outdo each other in proclaiming their love and support for the Fearless Leader. Stalin would give a speech and there would be hour or hours-long applause afterward. Nobody wanted to be the first one to stop clapping.
Anyway, I imagine that Sam Houston would have been killed had he advocated an end to slavery.
As it was, while he opposed secession, and he opposed Texas joining the Confederacy after secession, once the decisions were made, he supported Texas' government as a member of the CSA.
Here's his beautiful prediction of how the war would turn out: "Let me tell you what is coming. After the sacrifice of countless millions of treasure and hundreds of thousands of lives, you may win Southern independence if God be not against you, but I doubt it. I tell you that, while I believe with you in the doctrine of states rights, the North is determined to preserve this Union. They are not a fiery, impulsive people as you are, for they live in colder climates. But when they begin to move in a given direction, they move with the steady momentum and perseverance of a mighty avalanche; and what I fear is, they will overwhelm the South."