The Irish National Invincibles, usually known as "the Invincibles" were a radical IRB splinter group during the 1880s.
Murder in Phoenix Park
They hatched a plan to kill the Permanent Under Secretary at the Irish Office Thomas Henry Burke and it was Chief Secretary for Ireland Lord Frederick Cavendish's misfortune that he was walking with Burke when the assassins struck in Phoenix Park Dublin at 17:30 Saturday May 6, 1882, in what was to become known as the Phoenix Park Murders.
The Invincibles targeted Burke because he was a "Castle Catholic," who had been working for the British Government in a prominent position for many years, and was in their eyes a traitor to Ireland.
The assassinations in the park were initiated by Joe Brady knifing Burke, followed in short order by Tim Kelly, who knifed Lord Frederick. Both men used surgical knives. The British press expressed the outrage felt by many and demanded that the "Phoenix Park Murderers" be brought to justice.
The Invincibles' leader, James Carey, and Michael Kavanagh agreed to testify against the others. Joe Brady, Michael Fagan, Thomas Caffrey, Dan Curley and Tim Kelly were hanged by William Marwood in Kilmainham Gaol in Dublin between May 14 and June 4, 1883. Others were sentenced to serve long prison terms.
Retaliation
Carey was shot dead on board the 'Melrose Castle' off Cape Town, South Africa, on July 29, 1883, by Donegal man Patrick O Donnell , for giving evidence against his former comrades. O'Donnell was apprehended and escorted back to London, where he was convicted of murder at the Old Bailey and hanged on December 17 1883.
In song
The Invincibles and Carey are mentioned in the folk song "Monto (Take Her Up To Monto)":
When Carey told on Skin-the-goat,
O'Donnell caught him on the boat
He wished he'd never been afloat, the filthy skite.
Twasn't very sensible
To tell on the Invincibles
They stood up for their principles, day and night.