He joined the Irish Volunteers in the 1780s and held a number of minor public offices such as an inspector of wool and cloth but became involved in law enforcement as a sub-constable, billet master for the militia and a bounty hunter.

Avoiding pitched battles, Holt led a fierce campaign of raids and ambushes against loyalist military targets in Wicklow, striking at will and reducing government influence in the county to urban strongholds.

Holt rallied the remaining rebels and continued his United Irish guerrilla campaign as before allegedly even solving gunpowder shortages by inventing his own concoction known as 'Holt's Mixture'.

Eluding a number of large-scale sweeps into the mountains by the army following the collapse of the rising, Holt together with his younger rebel Captain Michael Dwyer, tied down thousands of troops and his forces were augmented by a steady supply of recruits, a significant proportion of whom were deserters from the militia.

Holt had largely held out in expectation of the arrival of French aid but news of the defeat of the French at the Ballinamuck together with his ill health brought about by the hardships of his fugitive life, age and family considerations prompted Holt to initiate contact through intermediaries as his wife, Hester Long's sister worked at Powerscourt for Lord Richard Wingfield, 4th Viscount Powerscourt with the Dublin Castle authorities with a view to a negotiated surrender.

He wrote in his Memoirs (Edited by Croker, 1838): "If I could have bought or borrowed a pistol, the world, I think, would soon have been rid of this man-killer, Foveaux, and with as short a warning as he gave to the two men he hung without trial."

Holt, however, was officially pardoned on 1 January 1811 and in December 1812, having sold some of his land and stock, with his wife and younger son took passage to Europe on the Isabella; also on board was Henry Browne Hayes.