As early as May, 1836, he warned the South, saying: "From the instant that your slaveholding States become the theater of war, civil, servile, or foreign, from that moment the war powers of the Constitution extend to interference with the institution of slavery." This sentiment he reiterated and amplified on various occasions.

The South was duly warned that an attempt to disrupt the Union would involve a war of which emancipation would be one of the consequences.

With the exception of Garrison and a few of his personal followers, abolitionists were unionists: they stood for the perpetual union of the States.
This is not the place to give an extended account of the Mexican War.

* There are, however, certain incidents connected with the annexation of Texas and the resulting war which profoundly affected the crusade against slavery.

Both Lundy and Birney in their missions to promote emancipation through the process of colonization believed that they had unearthed a plan on the part of Southern leaders to acquire territory from Mexico for the purpose of extending slavery.