Glad I found this thread. My grandfather, Tom Tierney, from Bohermore in Galway was one of the mutineers. He died when I was only one, so I never knew him.
He did feature in the book "The Connaught Rangers" by T.P. Kilfeather. I have the relevant passages here, so I hope it's okay to quote them.
Those who continued with the mutiny had a number of hours to reflect upon the seriousness of what they had done and what they now proposed to do. Perhaps most of them were thinking the same thoughts as Private Thomas Tierney, from Galway city. He had taken an oath of allegiance to King George V when he was scarcely eighteen years of age, urged on by appeals from posters, which were plastered on every blank wall in Galway. Those posters told of German atrocities in France and in Belgium. In the uniform of the king, he had served in the Inniskilling Fusiliers and the Connaught Rangers. Now the Black-and-Tans were doing in Ireland what the Germans were said to have done elsewhere. How, then, should a man regard an oath of loyalty to a king who permitted these things to happen? Private Tierney solved that problem with the answer: “I owe no further allegiance.”
At ten o’clock Colonel Deacon left his quarters and strode across the barracks, accompanied by all the officers of the battalion. “Men of the Rangers,” he barked, “I am about to order you to fall in. I do so in the name of the king. If you do not obey you will be dealt with by the full rigour of military law. All of you know what that means.”
Only two men refused to parade with the main body – Private Tierney, of Galway, and Lance-Corporal Willis, of Mullingar. His company quartermaster-sergeant approached Tierney and shouted, “fall in with your company.” The private replied: “Give the men in the cells the same option you have given me. If they are guilty of mutiny, I’m guilty too.”
Tierney was marched over to the cells in company with Willis. As they neared the other prisoners they were greeted with a wild Irish cheer.