Whig harmony by James Baillie, fl. 1838-1855. Published, 1848. A severe split within the Whig ranks, between partisans of Henry Clay and those of Zachary Taylor, preceded the partys convention in June 1848. Here Horace Greeley, one of Clays most influential northern supporters, tries to drive the party wagon downhill toward Salt River (a contemporary idiom for political doom). At the same time, a Brother Jonathan or Uncle Sam figure steers in the opposite direction, toward the White House. The chock that the cart has run into is a rock marked Wilmot Proviso, placed in the road by Congressman David Wilmot. The question of the validity of the proviso, an 1846 proposal to prohibit slavery in territories acquired during the Mexican War, became an important issue in the 1848 campaign.