His father had fought under Sir Phelim O'Neill against Charles the First.

The confiscation of the family estate had been ratified by an Act of Charles the Second.

No Puritan, who had been cited before the High Commission by Laud, who had charged under Cromwell at Naseby, who had been prosecuted under the Conventicle Act, and who had been in hiding on account of the Rye House Plot, bore less affection to the House of Stuart than the O'Haras and Macmahons, on whose support the fortunes of that House now seemed to depend.
The fixed purpose of these men was to break the foreign yoke, to exterminate the Saxon colony, to sweep away the Protestant Church, and to restore the soil to its ancient proprietors.

To obtain these ends they would without the smallest scruple have risen up against James; and to obtain these ends they rose up for him.

The Irish Jacobites, therefore, were not at all desirous that he should again reign at Whitehall: for they could not but be aware that a Sovereign of Ireland, who was also Sovereign of England, would not, and, even if he would, could not, long administer the government of the smaller and poorer kingdom in direct opposition to the feeling of the larger and richer.
Their real wish was that the Crowns might be completely separated, and that their island might, whether under James or without James they cared little, form a distinct state under the powerful protection of France.
While one party in the Council at Dublin regarded James merely as a tool to be employed for achieving the deliverance of Ireland, another party regarded Ireland merely as a tool to be employed for effecting the restoration of James.