In this and similar examples we see these three beings, the Bánánach, Bocánach, and Geniti glini appearing together, sometimes also with the fairy host and sometimes with the 'demons of the air' which is likely also a reference to the fairy host. All three were known to appear shrieking or screaming over or near battlefields.
|Cloch an Fhir Mhoir the menhir that marks where Cu Chulainn died in battle|
Bánánach - described in the eDIL as a 'preternatural being haunting the field of battle' (eDIL, 2017). The root of the name is suggested as Bánán which is further suggested as bán in this case probably meaning pale or bloodless, but also possibly meaning 'white'. We may perhaps postulate from this that these spirits appear pale or are clad in white, which would be inline with some other spirits associated with death. MacKillop suggests that the Bánánach is specifically a female spirit. In the Fianaigecht we are told that the Bánánach and Bocánach appeared with the Red-Mouthed Badb, one of the Irish war Goddesses further connecting them to the battlefield. Arguably we know the least about the Bánánach but if we translate the name as 'pale spirits' or 'white spirit-women' we may possibly tie them into other spirits like the White Ladies; although they may equally be connected to the Bean Sí. In some Irish folklore the Bean Sí are said to wear white, to shriek or wail, and to predict death and they are often connected back to the goddess Badb (MacKillop, 1998). This description does seem strikingly similar to the Bánánach, the biggest differences being the Bánánachs association with the battlefield and less explicit associations with death.
Bocánach - loosely described as a goat-like supernatural being, like the Bánánach it is known to haunt battlefields (eDIL, 2017). The name comes from the word Bocán and Boc, both meaning a he-goat. MacKillop considers them a type of goblin. It's possible that they may be similar to or related to the Púca and the Bócan who are both shape-shifting goblin-like fairies associated with goats. In the Cogadh Gaedhel re Gallaibh the Bocánach and the Bánánach appear on the battlefield with the Siabarsluag, the fairy host.
Geniti glini - a supernatural female specter who appears on battlefields, the name literally means 'Otherworldy-woman of the valley' (eDIL, 2017). O'Mulconry's Glossary gives us this about them: "genit glinde .i. ben i nglinn (gen .i. ben, glynnon .i. foglaid .i. banfoglaid bid a nglinn)" [Supernatural-women of the valley that is women of the glen (a girl that is a woman, glynnon that is a outlaw that is a female-outlaw living in the valley]. They are also sometimes called gelliti glini, translated as spirit of the valley, possibly due to a confusion between the words genit (supernatural woman) and geilt, a person driven mad in battle or a crazy person living in the wild (eDIL, 2017). These spectral women are strongly associated with shrieking on the battlefield as well as appearing there. Of the three named in this grouping the Geniti glini would seem to be the most obviously dangerous, particularly with O'Mulconry's direct equation of them with outlaws, using a word - foglaid - that also means reavers, plunderers, and later was a general term for an enemy.
Although we don't know too much about these spirits we can make some general associations based on when and how they appear in mythology. They usually seem to show up right before or during battles, and act to create or magnify feelings of battle-rage, frenzy, and madness. They appear sometimes with Nemain or Badb, Irish war Goddesses, who are both also associated with inspiring these things in warriors and armies. I think we can also safely say that they are not limited to the battlefield but are merely drawn to it, the way crows and ravens are drawn to carnage, since they also appear in conjunction with other mass groupings of fairies like the Siabarsluag. Although the information we have on them is obscure they do seem to have some connections to more well known spirits including the Bean Sí and Púca and it is at least possible that they might be early literary representations of spirits we later came to know by other names.
eDIL (2017) electronic Dictionary of the Irish Language
MacKillop, J., (1998) Dictionary of Celtic Mythology