Wikipedia handily translates into English and Gaelic.
Most Scots, and I'm sure a fair good few non-Scots, know about this auld sang, but for those that don't: "Robert Bruce's March to Bannockburn," known more commonly as "Scots Wha Hae," was written by Scotland's most celebrated poet Robert Burns in 1793. Though the speech itself is conjectural, it was written to the tune of "Hey Tuttie Tati," a traditional Scottish tune of ancient lineage, which was widely believed to have been played by the Scottish troops at Bannockburn.
You know that my pretensions to musical taste, are merely a few of Nature's instincts, untaught and untutored by Art. For this reason, many musical compositions, particularly where much of the merit lies in Counterpoint, however they may transport and ravish the cars of you connoisseurs. affect my simple lug no otherwise than merely as melodious Din. On the other hand, by way of amends, I am delighted with many little melodies, which the learned Musician despises as silly and insipid. I do not know whether the old air "Hey, tutti, tatie", may rank among this number; but well I know that, with Fraser's Hautboy, it has often filled my eyes with tears. There is a tradition, which I have met with in many places of Scotland, that it was Robert Bruce's March at the battle of Bannock-burn. This thought, in my yesternight's evening walk, warmed me to a pitch of enthusiasm on the theme of Liberty and Independance, which I threw into a kind of Scots Ode, fitted to the Air, that one might suppose to be the gallant ROYAL SCOT'S address to his heroic followers on that eventful morning.
- Robert Burns on Bannockburn, letter to George Thomson, dated 30th August 1793
As with so many of Burns' poems, the poem had topical political significance: on 30th August 1793, the trial of Glaswegian political reformer & lawyer Thomas Muir of Huntershill. Muir, along with many of the pro-Republican group "Friends of the People," was arrested on charges of sedition - for distribution of pamphlets and holding conventions arguing for then-radical parliamentary change to bring the vote to the common people. Since this took place shortly after the French Revolution, and in a year when France declared war on Britain, the British government took great pains to crush any remotely subversive challenges to the state. They certainly didn't want a Republican version of the Fifteen and Forty-Five. For in Britain, parliament was sovereign - the common people were not, and did not have the right to vote until centuries later. Muir was convicted, and sentenced to fourteen years transportation to Botany Bay.
When Bruce sent the letter for publishing to George Thomson just before the trial began, he wrote a postscript:
P.S. I shewed the air to Urbani, who was highly pleased with it, and begged me to make soft verses for it; but I had no idea of giving myself any trouble on the subject, till the accidental recollection of that glorious struggle for Freedom, associated with the glowing idea of some other struggles, of the same nature, not quite so ancient, roused my rhyming Mania...
Of course, Burns could never openly declare his Republican and Radical sympathies, or he would risk being sent to the prison colonies of Australia - or worse. Certainly he showed caution when the Morning Chronicle published the song on 8th May 1794, where he allowed it, but only "as a thing they have met with by accident, and unknown to (him.)"
Since then, the song has been a fixture of Scottish culture, the song of political parties, and one of several unofficial anthems for Scotland. I'm a personal advocate that it should be adopted in some official capacity, certainly over the glaikit "Flower of Scotland" and wan "Highland Cathedral," while "Scotland the Brave" is a bit too recent, and just not a patch on Burns. It's full of blood & thunder, as many anthems are, but focused on the idea of asserting nationhood not for the purposes of imperialism ("And not this land alone, But be thy mercies known, From shore to shore...") but freedom, the opposition of tyranny and slavery, and the sort of things worth defending.
As it was then, so it is now. Art is a natural expression for politics, and while I absolutely do not intend to insult the reader's intelligence by making Bannockburn into an overt allegory for current events, the applicability of several threads will not be difficult to discern. Regardless of what you see in Bannockburn, be it correlations with the 2014 Referendum, the worldwide struggle between increasingly oppressive regimes and populist movements, or the eternal dynamic of the privileged against the unprivileged, what's important is your own personal interpretation. I, as the author, cannot help but have my own sympathies, leanings, or intentions in writing the book - but you certainly don't have to share them, or even to agree that this or that is what was "really" meant.
So I've had my haggis, neeps & tatties, and having a wee break from Bannockburn to reflect on one of the truly greatest of Scots. I guess that makes three Roberts to pay tribute to!