Viewed in a global context, the American sectional struggle over slavery in the territories was part of a transatlantic upsurge in nationalist feeling in the 1840s and 1850s. Nationalist and republican revolutions swept through Europe in 1848 while wars of national unification or expansion raged in Mexico and South America. Almost everywhere, competing visions of national futures led to conflicts over territorial boundaries, forms of representative government, central versus local control, and degrees of personal freedom. Many Americans sympathized with overseas struggles against kings and tyrants, but when their own nation's expansion became intertwined with fierce sectional divisions over slavery versus freedom, its political leaders inched step-by-step toward a homegrown nationalist war. David Wilmot, author of the Wilmot Proviso, is an excellent example of a: