The first vice president to become president on the death of the incumbent, John Tyler (1790-1862) was derided by critics as His Accidency. Yet he proved to be a bold leader who used the malleable executive system to his advantage. In this biography of the tenth President of the United States, Edward P. Crapol challenges previous depictions of Tyler as a die-hard advocate of states' rights, limited government, and a strict interpretation of the Constitution. In pursuit of his agenda, Crapol argues, Tyler exploited executive prerogatives and manipulated constitutional requirements in ways that violated his professed allegiance to a strict interpretation of the Constitution. He set precedents that his successors in the White House invoked to create an American empire and expand presidential power. Crapol also highlights Tyler's enduring faith in America's national destiny and his belief that boundless territorial expansion would preserve the Union as a slaveholding republic. When Tyler, a Virginian, opted for secession and the Confederacy in 1861, he was stigmatized as America's traitor president for having betrayed the republic he once led. As Crapol demonstrates, Tyler's story is more complex, anticipating the modern imperial presidency in all its power and grandeur, as well as its darker side.