It was not alone through the medium of the _Northern Star_ that Neilson served the cause of the Catholics. He was active in his efforts to compose the differences between the Catholics and the Presbyterians, and to lay the feuds of the Peep o’ Day Boys and the Defenders. We learn from Tone’s diary that both Neilson and his wife were of the party which accompanied John Keogh and the other Catholic delegates, on their return from Belfast in July, 1732, to Rathfriland in order to meet some gentlemen of the neighbourhood with a view to restoring peace between the rival religious parties. He took part, with Tone and Keogh, in a similar expedition a month later. He was intensely interested in the work of the Catholic Committee and the plans for the Catholic Convention. It was probably in this connection that he became so intimate with Luke Teeling, of Lisburn, and his family, though their relations dated from a still earlier period when both men were working heart and soul to return to Parliament, as representative of the Co. Down, that ardent Reform candidate, the Hon. Robert Stewart—better known to history as Lord Castlereagh. In 1795 the terrible condition of affairs in the County Armagh, where the Catholics had been subjected to a barbarous persecution at the hands of the Peep o’ Day Boys without the slightest attempt on the part of the authorities, either to protect them or to restrain their savage aggressors, was rapidly reaching a tragic climax. Young Charles Teeling, then a lad of seventeen, got information that the Catholics, convinced that they could not be worse off than they were, were preparing to take the field openly against their intolerant foes. Relying on the influence which his family, from its standing, enjoyed among the Catholics of Armagh, he set off from Lisburn, without informing any one, in the hope of inducing the Defenders to desist from their disastrous purpose. He had not gone far, however, when he felt the need of some more mature and experienced head than that which sat on his own seventeen-year-old shoulders. His mind could suggest “none more desirable for the purpose than Samuel Neilson. He was the ardent patriot, the decided enemy to oppression in every shape and in every form; and the strenuous advocate, at all times and seasons, for the unqualified admission of his excluded fellow-countrymen, to their full participation in the blessings of civil and religious liberty. He was at the head of the, then, only liberal Press in Ulster; and his political influence however extended, was not more than commensurate with his labours in the public cause.” Teeling wrote to Neilson begging him to meet him in Portadown and thence to accompany him to the scene of the disturbances. Neilson complied without delay, but before he reached Portadown he was met by Teeling with the news that the Battle of Diamond had been fought, and that their intervention was too late.