E. Cobham Brewer 1810–1897. Dictionary of Phrase and Fable. 1898.
Selling the Pass.
This is a phrase, very general in all Ireland, applied to those who turn queen’s or king’s evidence, or who impeach their comrades for money. The tradition is that a regiment of soldiers was sent by Crotha, “lord of Atha,” to hold a pass against the invading army of Trathal, “King of Cael.” The pass was betrayed for
money. The Fir-bolgs being subdued, Trathal assumed the title of “King of Ireland.”
