On Feb 28, 1844, many important US officials - including President Tyler - were aboard the USS Princeton, when the gun the Peacemaker exploded, killing the Secretary of State and the Secretary of the Treasury and several others. So, what if Tyler had been killed in the explosion, alongside those two cabinet members and the others? Theoretically, Willie Person Mangum would have succeeded to the Presidency - how would that have gone? What might his Presidency look like, as he finishes Tyler's term? And does Mangum get nominated by the Whigs for reelection over Clay in that year's election?