Forget the Alamo: The Rise and Fall of an American Myth by Bryan Burrough, Chris Tomlinson, and Jason Stanford:
The loudest such voice, the abolitionist Benjamin Lundy, had traveled widely in Texas between 1832 and 1835, and knew many of those involved, from Juan Almonte to Sam Houston. When the war was over, he would write a pamphlet alleging that it was initiated by a conspiracy of Northern land speculators and Texas slaveholders whose intention was to bring Texas into the United States—but only after chopping it into as many as fifteen states, thereby upsetting the country’s fragile balance of free and slave states.
Lundy would find an adherent in the former president John Quincy Adams, by then a Massachusetts congressman and a leading abolitionist. “The war now raging in Texas,” Adams charged, “is a Mexican civil war, and a war for the re-establishment of Slavery where it was abolished. It is not a servile war, but a war between Slavery and Emancipation, and every possible effort has been made to drive us into this war, on the side of slavery.”