I think one error people make is in assuming the song is ABOUT the battle of Glenmalure, which it isn't. It is the TUNE that is supposed to be from A.D. 1580; it was reputed to be the march played by O'Byrne's pipers. But the battle of Glenmalure is clearly in the past from the song's point of view.

The song is actually about Fiach's whole career, referencing incidents as early as 1572 and as late as 1592, and seems to be set on the eve of one of his raids leading up to the nine years war--in the 1590s.

Did Fiach ever attack Carlow? Not that I know of. So this is a fictional or legendary raid being depicted, which is what has made this song so difficult to date! McCall says only that it is after Glenmalure, but not how long after. But there are clues...

First of all, if it's not about Glenmalure, why bring it up in the song? Glenmalure is brought up as the reason why MacCahir Og should take heart. The song is saying, "like the current Lord Deputy (William FitzWilliam), Lord Deputy Arthur Grey de Wilton had ALSO thought victory was sure, and it was Fiach that defeated him; so now that we are going up against another cocky Saxon Lord Deputy, FitzWilliam, it's good to have Fiach leading us."

MacCahir Og is Fiach's brother-in Law, Brian MacCahir Kavanagh, as the song's author confirms. The backstory here is that in 1572, Fiach and Brian were implicated in the murder of a landowner who was son-in-law to the Queen's Seneschal in Wexford. As a courtier, the Seneschal (Nicholas White) brought the matter to the Queen personally, and Fiach was locked in deadly dispute with White for over a year. It was during this period that William FitzWilliam, then Lord Deputy of Ireland, dispossessed MacCahir Og of his lands. Fiach's brother was also killed in 1572 as part of the campaign against the O'Byrnes and Kavanaghs. This is the "old disgrace," which gave both Fiach and MacCahir a grudge against both FitzWilliam and White.

FitzWilliam gave up the post of Lord Deputy in 1575, and was not in Ireland during the battle of Glenmalure--He was at Milton, Northants, his hometown in England (and was also governor of Fotheringhay castle during the imprisonment and execution of Mary, Queen of Scots). This is one reason why I think the song is not set right after Glenmalure; it makes it necessary to assume that the songwriter is calling Grey de Wilton "FitzWilliam" because his father had been called William, while the FitzWilliam who drove MacCahir Og out was William FitzWilliam. It would be both confusing and silly for the songwriter to refer to both men (who were not related, and one of whom was never actually referred to this way) as "FitzWilliam."

So, if FitzWilliam left Ireland in 1575, how could Fiach be fighting him after Glenmalure? Because FitzWilliam came back to Ireland and served as Lord Deputy again, from 1588 to 1594. It is in this period that the song is set, I believe. Probably it is before Fiach's sons took Ardree and burnt the Sheriff of Kildare to death, and so "Lord Kildare" is Pierce FitzGerald, who did indeed "curse and swear" at Fiach's exploits. It must certainly be before FitzWilliam left Ireland in August 1594.

The line "White is sick" makes it likely that we're speaking about sometime between 1590, when Fiach's old enemy Nicholas White, during a bout of illness, was arrested and sent to the Tower of London, and 1592, when White was executed. In 1592, also, FitzWilliam's star began to "fall low." He was accused of taking bribes, but defended by friends who were close to the Queen. Then in August, rumors of his death circulated in England--surely an inauspicious sign.

So all in all, I think it is likely that the words to the last verse are set in 1592, when White was sick (but still alive), And FitzWilliam's star was falling low, but not so low that he ceased to be a formidable adversary whose head was worth pursuing.

FitzWilliam's star fell still lower after White's death. He had been ill for some time, he pleaded with Elizabeth to recall him, and he had to appoint lieutenants to do the work of governing. Soon after his return to England in 1594, he became completely blind. He died in 1599.

Grey de Wilton, by the way, had left Ireland in 1582. He died peacefully in England, in his own bed, in 1593. He had been consistently employed by the queen, but kept at arm's length, and was never a true insider at court, due to rumors that he was a radical protestant. But he did fairly well for his last years, despite his failure in Ireland. He was a very well known man in his day; Spenser created a character, Artegall, who was a cipher for Arthur Grey de Wilton.

Finally, it was of course Fiach's head that was sent to Queen Liza, after he was killed in 1597. (Not dripping red, however; it had already been displayed for some time on the walls of Dublin Castle, and then pickled.) The Queen was not amused, and ordered that it be taken away. Presumably, McCall knew this story when he wrote the song, and put in the bit about sending FitzWilliam's head to Liza as a bit of irony.