What did the American Anti-Slavery Society think of the war with Mexico according to "A People's History of the United States"?According to Ch. 8

The American Anti-Slavery Society, like many in the North
did not like the war with Mexico at all.  The society and others felt that the only
purpose for the war was to help slavery.  They thought that the war would only help get
more territory in which white people would be allowed to own
slaves.

The society felt this because all of the land that
might be taken from Mexico would, of course, be in the South.  Since the South was where
slavery existed, it was natural to fear that any land added to the southern part of the
US would also have slavery.

For this reason, the
Anti-Slavery Society believed that the war was meant only to extend slavery.  Therefore,
it strongly disapproved of the war.