After an eighty-year record of remarkable unity in the face of threats from Irish Nationalism, Ulster Unionism suddenly fragmented in the late 1960s. This has been explained by reference both to the fissile nature of the Unionist pan-class alliance and to fundamental divisions over identity. Though important, these were not new factors and were compatible with a high degree of organizational unity. What ruptured the movement was Terence O'Neill's ambition to draw Catholics into the Unionist alliance, even at the expense of alienating some Protestant traditionalists. Increasingly, assimilatory Unionism, dominant in the Civil Service and civil society, confronted segregatory Unionism ensconced in the structures of the Unionist Party. This strategic dichotomy reached a climax with vicious Unionist in-fighting during the 1969 Crossroads election. O'Neill's assimilation-ism ultimately collapsed both because it was unconvincing to the ranks of Ulster Unionism, and because it failed in its primary aim of making inroads into Catholic support. O'Neill underestlimated the tenacity of both traditional Unionism and traditional Nationalism
