[4] Obtaining a first-class diploma, he first taught at Ballinamult, County Tipperary but then returned to Cork in early 1914 to take up a position at the Upton industrial school.

Devoted to the Irish language and honorary secretary of Knockavilla GAA club, Barrett did much to popularise both movements in the southern and western districts of Cork.

By this time he was also involved with Sinn Féin, in which role he attended the ard-fheis at the Mansion House in October 1917 and the convention of the Irish Volunteers at Croke Park immediately afterwards.

Behind him, lying on the pile of hay, were Michael Collins, Cathal Brugha, Austin Stack, Dermot Lynch, Eamon Duggan, Dermot O'Hegarty, Michael Staines, Liam Lynch of Cork, Terence McSwiney of Cork, Ernest Blythe, Joe McKelvey, Dick Barrett, Frank Barrett of Clare, Mick Brennan and one of his brothers of Clare, Sean MacEntee of Belfast, James Keaveney, Sligo, Alec McCabe of Sligo, Dory O'Connor, Dick McKee, Oscar Traynor, William M. O'Reilly and some of the McQuills of Dundalk, Brian O'Higgins, Laurence O'Toole, etc.

"Through planning and participating in raids and gun-running episodes, Barrett came into close contact with many GHQ staff during the War of Independence, thereby ensuring his own rapid promotion.

After the truce was declared on 11 July 1921, some prisoners went on hunger strike but Barrett called it off after a number of days on instructions from outside[11] as a decision had been made that able-bodied men were more important to the cause.

In November, he escaped by row boat alongside Moss (Maurice) Twomey, Henry O'Mahoney, Tom Crofts, Bill Quirke, Dick Eddy and Paddy Buckley.

Following the War of Independence, Barrett supported the Anti-Treaty IRA's refusal to submit to the authority of the Dáil (civil government of the Irish Republic declared in 1919).

This incident marked the official outbreak of the Irish Civil War, as fighting escalated around the country between pro- and anti-treaty factions.

In response, Liam Lynch, the Anti-Treaty Chief of Staff, gave an order that any member of the Dáil who had voted for the 'murder legislation' was to be shot on sight.

In reprisal for O'Higgins's role in the executions, the Anti-Treaty IRA killed his father and burned his family home in Stradbally, County Laois.

A monument was erected by old comrades of the West Cork Brigade, the First Southern Division, IRA, and of the Four Courts, Dublin, garrison in 1922[15] which was unveiled on 13 December 1952 by the Tánaiste Seán Lemass.