Organized Unionism at the end of the 19th century drew upon a long and complex heritage. It had roots in the Tory tradition, and built in particular upon an agile, well-resourced and electorally successful Irish Conservative party. Popular loyalism, defined from the 1790s, and evangelical religion, particularly significant from the 1820s onwards, were key agents for unity within Irish Protestantism and subsequently Irish Unionism. A modified Patriotism and Whiggery were also relevant to the intellectual hinterland of the Unionist movement. After 1885–86 the key themes within the development of Unionism were its increasing regional focus in Ulster, its popularization and commercialization, and its eventual militarization (by 1912–14). After partition in 1920, an Ulster Unionism dominated, caught between sporadic and countervailing pressures from populist sources, particularly the borderlands, and from London: these effectively delivered the fracturing of the movement after 1968, in the context of Nationalist mobilization.