He quickly established himself as a prominent organiser and was elected to the central committee in Belfast, becoming close to leaders such as Samuel Neilson, Thomas Russell, and Henry Joy McCracken. Hope was almost alone among the United Irish leaders in targeting manufacturers as well as landowners as the enemies of all radicals. In 1796, he was sent to Dublin to assist the United Irish organisation there to mobilise support among the working classes, and he was successful in establishing several branches throughout the city and especially in the Liberties area. He also travelled to counties in Ulster and Connaught, disseminating literature and organizing localities. Upon the outbreak of the 1798 rebellion in Leinster, Hope was sent on a failed mission to Belfast by Henry JoyMcCracken to brief the leader of the county Down United Irishmen, Rev. William Dickson, with news of the planned rising in Antrim, unaware that Dickson had been arrested only a couple of days before. Hope managed to escape from Belfast in time to take part in the battle of Antrim where he played a skillful and courageous role with his "Spartan Band", in covering the retreat of the fleeing rebels after their defeat.
After the defeat
Hope managed to rejoin McCracken and his remaining forces after the battle at their camp upon Slemish mountain, but the camp gradually dispersed, and the dwindling band of insurgents were then forced to goon the run. He successfully eluded capture, but his friend McCracken was captured and executed on 17 July. Upon the collapse of the general rising, Hope refused to avail of the terms of an amnesty offered by Lord Cornwallis on the grounds that to do so would be "not only a recantation of one’s principles, but a tacit acquiescence in the justice of the punishment which had been inflicted on thousands of my unfortunate associates".
After 1798
He lived the years following 1798 on the move between counties Dublin, Meath and Westmeath but was finally forced to flee Dublin following the failure of Robert Emmet's rebellion in 1803. He returned to the north and evaded the authorities attentions in the ensuing repression by securing employment with a sympathetic friend from England. He is today regarded as the most egalitarian and socialist of all the United Irish leadership. He died in 1846 and is buried in the Mallusk cemetery, Newtownabbey. His gravestone features the outline of a large dog, which supposedly brought provisions to him and his compatriots when they were hiding following the Battle of Antrim.
