We all learned in school about the Danzig Corridor and its role as one of the catalysts of the second World. Less well publicised, then and still, was the Donegal Corridor, although that one played at least some part in Germany’s subsequent defeat.
I drove through it at the weekend, en route to a football match. And even today you can easily understand its strategic importance.
Actually, to be more precise, I drove under it, because unlike the one in Poland, the Donegal Corridor was a purely aerial phenomenon. But in any case it began somewhere near Belleek, Co Fermanagh, officially the UK's most western village. Then, like me on Sunday, it continued towards Ballyshannon, in Donegal, only three or four miles away.
This was a world of difference in 1941, during the Battle of the Atlantic. Bitterly regretting the loss of the Irish "treaty ports", the British government pressed Eamon de Valera to allow Allied flying boats take the short cut from upper Lough Erne to the ocean. De Valera agreed, quietly, but with fatal consequences for German U-boats and, indirectly, for the battleship Bismarck.
That is not, by any measure, the only front-line Ballyshannon has been on over the centuries. The Vikings had a corridor here too – the river Erne – to invade the interior. Red Hugh O’Donnell used it as a base against the English.
And of course the province of Connacht has always been barely a spear’s throw away, to the south.
But temporal frontiers aside, the town also seems to have one of the more permeable borders between the natural and supernatural worlds. Among the graves in St Anne's churchyard is that of poet William Allingham, who wrote one of the more famous verses about fairies: "Up the airy mountain,/Down the rushy glen,/We daren't go a-hunting/For fear of little men."
The lines have been much quoted ever since, making appearances in the movie Willie Wonka and the Chocolate Factory and the work of Terry Pratchett, among other places.
Allingham also wrote a poetic version of a ghostly event that the real-life Robert Stewart, aka Lord Castlereagh, claimed to have experienced while staying in the town's barracks in 1793. It involved a "radiant boy" – a younger, male version of the banshee – who was said to presage worldly success but also a violent end for anyone who saw him.
Allingham called it the “Goblin Child of Belashanny”.
Walter Scott, who heard the story from Stewart, wrote about it too. As for Stewart, he did indeed go on to great, if controversial, renown for his part in putting down the 1798 Rebellion, then forcing through the Act of Union and, later, for repressive policies that led to England's Peterloo massacre.
This in turn inspired poetry, of a less flattering kind. "I met murder on the way - he had a mask like Castlereagh", wrote Shelley. And after Stewart, by then considered insane, took his own life in 1822, Lord Byron composed a mock epitaph: "Posterity will ne'er survey/A nobler grave than this/Here lie the bones of Castlereagh/Stop, traveller, and piss."
There is not much left today of the barracks where Stewart had his vision. But what there is creates one of the odder approaches to a GAA pitch anywhere in Ireland.
Both are on a hill overlooking Ballyshannon. So after attending the Donegal-Monaghan game on Sunday (in which, faced with home team’s normally-impenetrable defence, the visitors had somehow negotiated overflight rights for a late, equalising goal), hundreds of us retraced our steps back down a steep, narrow, winding corridor into the town.
And never mind the Goblin Child, I had a vision of disaster if anyone started a stampede.
Luckily, like the game itself, it finished peacefully.
After a walking tour of the locality, which included paying our respects to the statue of another local poet, Rory Gallagher, my travelling companion and I decided to visit one of the nearby beaches.
It was an unseasonably balmy day, after all. So we did as the Orangemen of surrounding counties do every July and took the President’s Highway, to Rossnowlagh.
This is another Donegal Corridor: at least for those who have to cross the Border to reach it every year. And even in March (as opposed to on a march) you could see the attraction. The switch to summer time had stretched an already glorious evening out by another hour. The beach was still bright at 8pm. Then, spectacularly, the whole horizon went orange, three months prematurely, and we witnessed our first Atlantic sunset of 2017.