“JJ (Ginger) O’Connell, former engineering student at UCD and Deputy Chief of Staff of the Free State Army, is captured by forces under the command of fellow UCD graduate Rory O’Connor and held at the Four Courts garrison. “https://centenaries.ucd.ie/1912-1923-timeline/#year-11
When Michael Collins issued his final ultimatum to the Four Courts garrison to leave the building, it not observed. The IRA unit under Rory O’Connor continued to hold out, knowing that an attack was imminent. The very next morning, June 28th the Free State Army launched their attack, commencing the first phase of the Civil War.
Dublin Evening Telegraph 28 June 1922