Nice, atmospheric image by artist Joseph Feely depicting a spear volley by a group of Ceithrenn (normally referred to as ‘Kern’ by non-Irish speakers).
I get a lot of overseas fantasy militarists visiting the website who get quite turned on by the idea of Ceithrenn. Some of these have quite strange views about what they were and how they operated (usually based on information from other non-Irish-speaking militarists), much of which doesn’t align with what we know of them from a historical context.
As a general rule, I wouldn’t put too much fate in anything you see on the internet relating to Ceithernn unless it comes from a recognisable Irish historian/academic.