Coming from Mass, three IRA flying column boys are caught "on a bridge near Gortaglanna ... In the Valley of Knockanure" in May 1921. The three are named. They are beaten and shot.
The "Black and Tans" were British reinforcements to regular British soldiers sent to Ireland in 1920. The "Auxiliary Cadets" were veteran British army officers sent to help the Black and Tans. (source: _Michael Collins: A Man Against an Empire_ copyright by and available on the History Net site). For more information see RBW note for "The Bold Black and Tan" - BS
The IRA's "flying columns" were not quite what is usually meant by this term. They were guerrilla groups, usually of only a few dozen men, who did most of their damage in small raids on supply lines. Nonetheless, they were very effective -- the main strength of the rebellion, in fact. As a result, they were subject to severe punishment when caught.
This particular atrocity was fairly typical of the Black and Tan war -- minor enough that it is not mentioned in any of the history books I checked. Sadly, there are many similar incidents recorded. This one is remembered because it caught the fancy of poets.
The existence of two songs called "The Valley of Knockanure," both referring to the same event, has caused some confusion. (Not least in earlier versions of this index).
O Lochlainn lists the author of this as Tim Leary of Listowel, while Tunney lists the author of "Knockanure (II)" as Brian McMahon of Kerry. But the Digital Tradition lists "Knockanure (II)" as by "Tim Leahy" (presumably an error for Leary) Tunney's claim of (II) for McMahon is supported also by Soodlum's Irish Ballad Book. - RBW