the war between Mexico n US was fought between 1846 to 1848.
Frederick Douglas was traveling in Ireland n England during that time.
Abraham Lincoln spoke out against the war n was a member of the Whig party which opposed the Manifest Destiny.
John Adams was long dead.
Henry David Thoreau was against the war n refused to pay tax cuz' of it. But hes an anarchist n promoted civil disobedience which had nothing to do w the manifest destiny.
so the ans is Abraham Lincoln