On the morning of 15th May, 1922, over 1,000 recruits of the newly established Civic Guard suddenly broke ranks during Commissioner Michael Staines’ TD address at Morning Parade in the training depot at Kildare Barracks. The recruits immediately set about raiding the armoury while Staines and his senior officers withdrew under armed protection and evacuated the barracks much to the annoyance of Michael Collins, the Chairman of the fledgling Provisional Government. For almost seven weeks, Collins and the mutineers struggled to reconcile their differences in the midst of the Irish Civil War. Both sides were unaware that their efforts to resolve the dispute were thwarted by a group of anti-Treaty Civic Guards intent on destroying the new force. This book investigates the reasons why the earliest recruits of the Civic Guard took up arms against their own masters and brought about a significant security risk that had direct implications for both the civil war and the future structure of the its successor, An Garda Siochana.