The "orange lodges" were (and are) Protestant fraternal organizations that formed in Deasy's beloved Ulster to celebrate the memory of William of Orange, to violently intimidate Catholics, and to ensure the continuation of British Protestant rule in Ireland. It is highly misleading, at best, to say that they "agitated for repeal of the union."
The lodges formed in the early 1790s, and soon joined to make up a united Orange Order, Lodge, Institution, or Society that survives to the present day and still organizes supremacist marches through Catholic areas in the north. While it is true that the Order opposed Union when the idea was first being proposed in the 1790s, the Act of Union was not passed until 1800. Orangemen quickly came to support it, and never "agitated for repeal." In the 1870s and 80s, when the Home Rule movement gathered momentum, the Order was inflexibly opposed. Its support for Union with Great Britain has continued throughout the history of Northern Ireland, from 1922 to the present.
The closest American analogy to the early Orangemen is the Ku Klux Klan. Orange forces randomly attacked and murdered Catholics, destroyed cottages, invaded churches, and mounted public displays of might. There are significant differences: the Americans were reversing the effects of a war that the South had lost, while the Ulster Protestants were preserving the fruits of a war that King William had won; and American blacks could not offer any organized resistance like that mounted by the Irish Catholics called Defenders. Still, Orange opposition to Irish Catholic autonomy has always been unambiguous and coercive. Deasy's picture of Orangemen as making common cause with nationalists like O'Connell could not be more inaccurate.