So this is the other side of the question I asked in another recent review. Do you rate a book more highly if it attempts to do something quite ambitious and doesn't quite succeed, or if it has more modest ambitions and fulfills them admirably? This is the more ambitious book that didn't always succeed.
The ambitious part; a historical novel set in Ulster at the time and among the heros of the Táin Bó Cúailnge - the Cattle Raid of Cooley - one of the foundational hero tales of Ireland. Big task. Like retelling the Illiad as a historical novel.
Setting yourself such a task runs the author into some problems. What do you do with the mythological and fantastical elements? The interventions of the Tuatha de Danaan, the Morrigan, Lugh, the curse that causes all the warriors of Ulster to fall down with cramps so only Cúchulainn is left to defend the border? Finney writes this as an historical, not a fantasy - so she has to find some way to make sense of all that, to write this as history that might have inspired the myths rather than as myth.
The other big problem is that the early history of Ireland is a little murky, and was more so in 1977 when this was written. So there are fairly significant elements that just aren't known. Do you gloss over the fact that you don't know exactly what a chariot of the time looked like? Chariots are an important part of the story, you can't leave them out. Do you make something up? Do you have someone conveniently come in and interrupt when the chariot discussion is going on?
So I recognise the difficulty of what she is doing, and feel inclined to cut her a little slack if it doesn't always work. Sometimes it works admirably. Sometimes I feel like I'm actually seeing the world as an Irishman of the hill forts. So for that, and for the recognition of the difficulty of what she is trying to do, four stars.
But not five, because sometimes the whole effort bogs down into these eye twitching boggles of paragraphs about how Finn Mac Ap called upon his seven kinsmen to help him against Ap Mac Finn but they were under geas not to go against the descendants of Ap being as how they owed a boon to the husband of the sister of the nephew of the Mac Finn who owned the fish run beside the house of Lugh Mac Bolgh, who stood apart from the whole matter, not wanting to risk his alliance with the ... aghhh. I realize that this comes from her source material, and that she has to somehow reflect the network of kinship and alliance in which these people lived, but sometimes it just gets out of hand and brings the narrative to a screeching grinding halt.