Gunman believed to have killed Michael Collins was granted military pension

Denis ‘Sonny’ O’Neill: RIC man, spy, IRA volunteer and, almost certainly, the Big Fellow’s assassin

The military service pension collection archivists highlight three people who made lasting impacts on Ireland's formation: Agnes McCarthy, Sean Hyde and Dennis (Sonny) O'Neill, the man believed to have killed Michael Collins. Video: Enda O'Dowd


The man widely credited with shooting Michael Collins at Béal na Bláth in 1922 was awarded a State pension for his actions in the War of Independence and Civil War.

Confirmation that Denis ‘Sonny’ O’Neill , a native of West Cork, took part in the ambush is contained in files from the Military Archives released yesterday.

The question of who gunned down the revolutionary leader in his prime, has haunted post-war Irish politics. O’Neill was finally publicly named as the shooter Colm Connolly’s 1980s documentary ‘Shadow of Beal na Blath’.

There had been rumours since 1922 that O’Neill, a trained marksman who fought in the British Army in the First World War, was the one who fired the fatal shot.

In a previously unseen and rare military intelligence file contained in the Military Service Pensions Collection he cited his presence at the Béal na Bláth ambush in west Cork on August 22nd 1922 . He did not say he was the one who actually shot Collins.

In another part of his statement O’Neill disclosed that he had met Collins on a number of occasions before the ambush. He was first introduced to Collins in December 1920 and had further contact with him during 1921.

O’Neill, a former RIC man who was wounded fighting with the British army in the first World War, joined the IRA in December 1918.

During the War of Independence, he moved from Cork to Dublin to enrol in the College of Science in Dublin and came to the attention of the man who he eventually would kill at Béal na Bláth.

Spy material

His services to the British crown made him an excellent spy when he switched sides and he supplied valuable information on the Igoe gang which was formed after Collins’s men wiped out the Cairo Gang on Bloody Sunday in 1920.

O’Neill took the anti-Treaty side in the Civil War and assumed a training role in a cavalry column. Unlike many intelligence files from the period which were destroyed in 1932, his remains intact.

He was described as having a “very downcast appearance, hardly ever smiles, never looks a person in the face when speaking” though, significantly, he was also a “first-class shot”.

Another file describes him as a “very unscrupulous individual” and a “most aggressive enemy of the present government”.

When the Civil War broke out, O’Neill moved back to Cork and was officer commanding training in the Southern Division of the IRA in Mallow.

In his testimony before the military pensions archive board, O’Neill said he “accidentally ran into the Ballinablath [SIC]thing, Tom Hales and myself”. Hales was a well-known republican whose brother Seán had taken the pro-Treaty side in the Civil War. “We heard about the party going through in the morning. They took a wrong turning and went into Newcestown. We went down to look at the position in Ballinblath [SIC].”


Collins was killed when his convoy was returning to Cork city from Mallow at about 7.15pm on the evening of August 22nd. He had passed the same way earlier that morning and an IRA column were waiting for him to return the same way. At dusk, the IRA volunteers were about to retire for the night when the convoy returned.

When the ambush began, Collins disregarded the advice of his aide-de-camp Emmet Dalton to drive on and ordered his men to return fire. Collins was firing from behind an armoured car but, when he unwisely ventured out into the centre of the road, he was hit by a single gunshot to the head. He died instantly.

Unsurprisingly, in front of the military pensions board, O’Neill is neither asked about, nor volunteers any information on, the killing of Collins.

He was more candid when he gave an interview to the senior IRA intelligence officer Comdt Seán Dowling in the immediate aftermath of the ambush, admitting that he pulled the trigger

. During the making of Connolly’s documentary, the last survivor of the Béal na Bláth ambush, Jim Kearney, told the film-maker off-camera that it was O’Neill who killed Collins. O’Neill received a pension in the rank of captain for 5¼ years’ service in 1939.