| Date | | | |
| 9-Dec-1865 | | John Haltigan sentenced for 7 years. | |
| 12-Dec-1865 | | Jeremiah O'Donovan Rossa sentenced for life; and the Judges adjourn until 4th January, 1866. | |
| 16-Jan-1866 | | In consequence of the discovery of concealed arms, the county and city of Dublin is "proclaimed," no person is allowed to appear with firearms, and the police are empowered to search for arms. | |
| 2-Feb-1866 | | The Special Commission for the trial of Fenian Conspirators terminates. Thirty-six prisoners were convicted or pleaded guilty, three were acquitted, and in one case the jury disagreed. | |
| 9-Feb-1866 | | Fenian ammunition manufactory discovered. A man named George Clarke, who resided in Jervis street, is murdered, between the fifth and sixth locks of the Royal Canal; it is supposed on account of his having been suspected of giving information to the police in reference to the concealment of arms. | |
| 17-Feb-1866 | | An Act for the suspension of the Habeas Corpus Act in Ireland passed both Houses of Parliament, and on the same day 120 persons are arrested in Dublin. | |
| 18-Jul-1866 | | Departure of the Earl of Kimberley, Lord Lieutenant of Ireland, consequent on the resignation of Earl Russell's Administration. | |
| 20-Jul-1866 | | Arrival of the Marquess of Abercorn, K.G., Lord Lieutenant of Ireland. | |
| Nov-1866 | December | The Fenian agitation being revived by the appearance of emissaries from the United States and elsewhere, various persons are arrested under the Habeas Corpus Suspension Act; seizures of arms by the police take place ; naval and military reinforcements are promptly sent to Dublin and other parts of Ireland. These timely preparations towards the end of the year, paralyse the movement. | |
| 30-Nov-1866 | | The new parish church of St. Andrew (erected on the site of the old Round Church which was burned some years since) consecrated by the Archbishop of Dublin, in the presence of His Excellency the Lord Lieutenant and n large congregation. St. Andrew's is a beautiful building, of cruciform shape and Gothic style. | |