6 March 1923, 5 Free State soldiers, including Captains Michael Dunne and Joseph Stapleton of Dublin Brigade, were killed in Knocknagoshel, Co Kerry, by a booby trap mine planted by the Kerry IRA. The target of the trap was a particular local fellow by the name of Paddy "Pats" O'Connor who, according to the IRA, was a notorious torturer of prisoners. O'Connor joined the Free State army because of the treatment of his father by the local IRA.

The Dublin Guards, who had been in Kerry since the previous August, were commanded by Paddy O'Daly. He was furious over the booby trap and it subsequently became clear that he was responsible for what took place following the Knocknagoshel incident.

At around 2am on March 7th 9 IRA prisoners, many of whom had been tortured, were brought to Ballyseedy wood where they were told that they were to remove an "irregular road block". However, it was clear to the men what was in store for them when they had been shown 9 coffins in the barracks. Each were offered a cigarette and told it be "the last you'll have". They were then tied together to the mined road block and blown up. Some of the men were still alive and were finished off by grenade and machine gun.

Unbeknownst to the Free State troops one man was blown clear and managed to escape. His name was Stephen Fuller (to become a FF TD in 1937). Because the bodies were so badly mangled all nine coffins were filled with the remains of the 8 who perished. This was to lead to a near riot in Tralee when the coffins were handed over the the families at the gates of Ballymullen barracks. The families broke open the coffins to try and identify the remains.

Later on the same day a very similar incident took place at Countess Bridge in Killarney where 5 IRA prisoners where asked to remove a mined road block which was also blown up. Three of the men who lay wounded were finished off by grenade. Again, amazingly, a fifth man named Tadhg Coffey, survived and escaped.