Despite expressing some British patriotism during his early years, Barry's views slowly began to change towards Irish republicanism.

In his memoir, Barry stated that this started shortly after he heard about the Easter Rising in 1916, though records show that after the war he made two unsuccessful attempts at joining the British Civil Service.

Barry then became the column's overall commander and would lead the Brigade in a number of successful attacks against British forces, including the ambushes at Kilmichael and Crossbarry.

Following the outbreak of the civil war, Barry was briefly imprisoned by the new Irish Free State but managed to escape and go on to command Anti-Treaty forces in the southern regions of Ireland.

When it became clear that victory could not be achieved, Barry proposed that the Anti-Treaty IRA should lay down their arms, which led to frequent clashes with Liam Lynch.

[4] Barry was first educated at Ardagh Boys' National School before later attending Mungret College in County Limerick from 25 August 1911 to 12 September 1912.

[6] In 1915, during Ireland's involvement in World War I, he enlisted in the Royal Field Artillery at Cork and became a soldier in the British Army.

[9] In April, while his brigade was attempting to break the Turkish Siege of Kut, Barry first heard of the Easter Rising, which he describes in his memoir as "a rude awakening".

[12] On his return to Bandon in County Cork, Barry first began to study Law and Business Affairs, while at the same time maintaining friendship with local ex-servicemen's organisations and building connections to the Irish republican movement.

Initially Barry seemed proud of his wartime British Army service and hoisted a Union flag at Bandon on the first anniversary of the war's end in November 1919.

[14] A possible third reason was the brutal beating of IRA members Tom Hales and Patrick Harte, both of whom were from Bandon, by officers of the Essex Regiment during an interrogation in July 1920.

[24] Barry was hospitalised for a time after the Kilmichael action and martial law was proclaimed in County Cork and across much of the province of Munster in response.

[25] In one such instance in February 1921, Barry's column attempted to launch an attack on the RIC Barracks in Rosscarbery, billeting at Burgatia House, which was owned by a Loyalist family, to avoid detection.

Barry recalled his initial reaction as "dazed and uncertain of the future" but relief that the "days of fear were ended, at least for a time".

In March 1922, he and his men occupied barracks in Limerick in defiance of the new Irish Free State government, and it looked as if fighting would break out until Liam Lynch IRA Chief of Staff arrived and defused the situation.

[39] In May 1922, Barry along with Rory O'Connor and Ernie O'Malley seized a convoy of arms intended for the new Free State police force and drove it to the anti-Treaty IRA headquarter in the Four Courts in Dublin.

[39] On 28 June 1922, the Irish Civil War formally broke out between Pro- and Anti-treaty factions when Free State forces opened fire on the Four Courts.

Barry had voiced the opinion that, at the start of the civil war, while the Republican side was stronger, it should have taken over Dublin and the major cities and forced a new confrontation with the British.

In September of that year, however, he escaped from an internment camp at Gormanston in County Meath and travelled south, to take command of the anti-Treaty IRA Second Southern Division.

By February 1923, Barry increasingly argued with Liam Lynch, the Republican commander in chief, that the war should be brought to an end, as there was no hope of victory.

[43] Nevertheless, the Free State government never formally acknowledged the end of the civil war marked by the republicans' ceasefire and dump arms order.

[45] According to historian Brian Hanley, Tom Barry left the IRA shortly after the Executive had narrowly defeated his proposal (of March 1923) to hand over its arms to prevent further bloodshed between nationalists.

He initially proposed cooperation of the IRA and Fianna Fáil, the party led by erstwhile republican leader Éamon de Valera, especially against the Blueshirts, a militant movement born out of Pro-treaty civil war veterans.

In fact, in January 1937 he had taken a trip to Germany seeking German support, which was assured to him subject to the condition that the IRA limit its actions to British military installations once war was declared.

[citation needed] In 1942, following the fall of Singapore to the Imperial Japanese Army, Barry purportedly sent a telegram to the British commander Arthur Percival, who was his opponent during the war of independence, "congratulating" him on the defence.

[57] On 10 July the same year, Barry attended the unveiling of the monument to the Kilmichael ambush along with other surviving participants, where they formed a guard of honour during the ceremony.

[58] Barry took a militant line on the Northern Ireland conflict post 1969, arguing in 1971 that peaceful means would never achieve Irish unity and supporting armed action there.

[59] He was against the tactics of the Provisional IRA's campaign, particularly their use of car bombs against civilians, though he did defend attacks on British soldiers on active duty in Northern Ireland.

It describes his Brigade's activities, such as the ambushes at Kilmichael and Crossbarry, as well as numerous other less known actions which were directed against the British Army, Black and Tans, the Auxiliary Division and the Royal Irish Constabulary.