During the American Revolution, abolitionism became a social movement for the first time. Amid their appeals for liberty and equality, Americans increasingly realized the contradictions of owning slaves, and even prominent Founding Father slaveholders spoke of the need to find ways to reform or phase out the institution. The first explicit abolitions in the world occurred amid the War of Independence. By the early republic, antislavery societies became numerous – though the cause’s momentum was thwarted in the closed-door Constitutional Convention and the rise of cotton in the American South in the 1790s motivated a new spread of slavery.