Four days later he escaped from Kilmainham Gaol along with Ernie O'Malley and Frank Teeling.

Donnelly took the anti-Treaty side in the Civil War and took part in the Battle of Dublin.

[4] He founded the National Association of the Old IRA in an attempt to mend some of the rifts in the Republican Movement.

He was a member of the provisional National Executive of the Republican Prisoners' Release Association.

[6] As one of the most senior surviving veterans of the Rising, he played a prominent role in the 50th anniversary commemorations in 1966.