In a memorandum sent by General Sir John Maxwell to the then British Prime Minister, Herbet Asquith, the following description was provided for Michael Mallin:

This man was second-in-command of the Larkinite or Citizen Army with which organisation had had been connected since its inception. He was in command of the rebels who occupied Stephen's Green and the College of Surgeons. At these places serious encounters took place and there were many casualties both amongst the military and civilians. He surrendered on 30 April 1916 and was accompanied by a body of 109 rebels all of whom were armed.

Michael Mallin was tried by Field General Courts Martial on 3 May 1916. The proceedings are contained in the PRO document WO 71/353.

Court Martial Proceedings

The members of the courts martial were Colonel E.W.S.K. Maconchy (President), Lieutenant-Colonel Bent and Major F.W. Woodward.

At his trial, Michael Mallin faced two charges to which he pleaded not guilty:

1. " ... did take part in an armed rebellion and in the waging of war against His Majesty the King, such act being of such a nature as to be calculated to be prejudicial to the Defence of the Realm and being done with the intension and for the purpose of assisting the enemy."
2. "Did attempt to cause disaffection among the civilian population of His Majesty."

The 1st Witness was No. C212 Police Constable John O'Connell (Dublin Metropolitan Police) who stated

I know the prisoner Michael Mallin. There is a paper called "The Workers Republic" in which it has been stated th the prisoner is Chief of the Staff of the Citizen Army. I have known the prisoner about 9 or 10 months. I have seen marching with the Citizen Army and he has marched with James Connolly and the Countess Markievicz and has led them in company with James Connolly.

When cross-examined by Mallin the witness said that he did not know whether the prisoner was in command James Connolly when marching with the Citizen Army. I never saw him as a drill instructor or a band instructor. I never heard him make any speech at all. I have only seen it in the paper that the prisoner was Chief of the Staff of the Citizen Army.

When asked by the court's President to explain the relationship between the Citizen Army and the Irish Volunteers the witness said that the Citizen Army and the Irish Volunteers are two distinct bodies. The Citizen Army is under the control of James Connolly. There is a slight difference in the uniform of the two armies.

The 2nd Witness was No. C128 Police Constable C. Butler (Dublin Metropolitan Police) who stated

I know the prisoner now before the Court and have known him for 6 or 8 months. I have seen him marching with the Citizen Army wearing the uniform in which he is now dressed. On one or two occasions he wore a revolver on his waistbelt. He marched with James Connolly at the head of the Army and also with the Countess of Markievicz. I saw him on Easter Monday about 11.50 am he was in front of Liberty Hall dressed as he is now. He seemed to be busy generally organising the Citizen Army and there was a large crowd present.

When asked by the accused what he was doing, the witness stated that he led a section across the footbridge in the direction of St. Stephen's Green and the College of Surgeons. The witness also stated that the accused appeared to be on friendly terms with the police present at the scene.

The 3rd witness was Captain H.E. Wheeler who stated

I was on duty on 30th April outside the College of Surgeons. A body of prisoners surrendered to me between 12.30 p.m. and 1 p.m. The prisoner and the Countess of Markievicz came out of a side door of the College. The prisoner was carrying a white flag and was unarmed but the Countess was armed. The prisoner came forward and viluted and said he wished to surrender and this is the Countess Markievicz. He surrendered and stated he was the Commandant of the garrison. I took over the garrison which consisted of prisoner, Countess Markievicz, 109 men and 10 women. I found them in the College and they laid down their arms under my directions.

In his defence, Michael Mallin stated

I am a silk weaver by trade and have been employed by the Transport Union as band instructor. During my instruction of these bands they became part of the Citizen Army and from this I was asked to become a drill instructor. I had no commission whatever in the Citizen Army. I was never taken into the confidence of James Connolly. I was under the impression we were going out for manoeuvres on Sunday but something altered the arrangements and the manoeuvres were postponed till Monday. I had verbal instructions from James Connolly to take 36 men to St. St. Stephen's Green and to report to the Volunteer officer there. Shortly after my arrival at St. St. Stephen's Green the firing started and the Countess of Markievicz ordered me to take command of the men as I had been so long associated with them. I felt I could not leave them and from that time I joined the rebellion. I made it my business to save all officers and civilians who were brought in to St. Stephen's Green. I gave explicit orders to the men to make no offensive movements and I prevented them attacking the Shelborne Hotel. I also indignantly repudiate any idea of assisting Germany

The 1st Witness produced in Mallin's defence was Mr L.J. Kettle who stated

The prisoner prevented my death by shooting. I was treated with every possible consideration and also I saw he did the same for any other prisoners who were brought in.

When cross-examined by the prosecution, the witness said that he had been taken prisoner on Monday afternoon 24th April and was taken first to Stephen's Green and Mallin appeared to be in command. I heard a good deal of firing but actually did not see the firing myself. The witness then added that although he could have been released at anytime but was finally released after the surrender.

Court Martial Verdict

Michael Mallin was found guilty and not guilty of the 1st and 2nd charges respectively, and was sentenced to death by shooting. This sentence was confirmed by General Maxwell. Between 3.45 and 4.05am on 8 May 1916, Michael Mallin was shot in the former stonebreakers yard at Kilmainham Prison. His remains were later buried in Arbour Lane Cemetery.