To hear that Chelsea Manning was a Celt from an Irish/Welsh background reminded me of an ironic connection to Celtic history. People will know of the racist insult "to welsh or welch on someone" I think Clinton actually banned it during his presidency. The meaning is to renege on a promise and sometimes a bet, or to betray someone.
The origin of the phrase comes form the Middle Ages, when the English used to dragoon Welshmen into the English armies. Since none of the Welsh spoke English, they were organized into Welsh regiments. But the problem for the English was they could never rely on them. In battle after battle, the Welsh soldiers would turn on the English troops and start attacking them.
The most famous of these was the Battle of Falkirk for Scottish independence from the English, portrayed by Mel Gibson in Braveheart. Before the battle began the Welsh soldiers turned on the English troops, slaughtering hundreds of them and threatening to go over to the side of William Wallace's Scottish army. Finally, the Welsh leaders cut a deal with the English and participated in the battle, as did hundreds of Irish sling-shooters also on the English side.
But another irony, it made me think of is not only the Welsh/Irish connection, but the Scots/Welsh connection, although it might irk some Scottish readers. And that was that Wallace's name meant "Welshman" in the old English of the time, so he would have been known known as William the Welshman, and he is descended from a Welsh family. Up to the 13th century most of southern Scotland was Welsh-speaking. It was referred to by the Welsh as North Wales and the "Old North". Glasgow is actually a Welsh word meaning the green hollow.
The region of Cumbria, which includes the Lake District and stretches down from South West Scotland to Liverpool and modern North Wales was also Welsh-speaking - the name Cumbria comes from the Welsh word for Wales,“Cymru.”
As you probably guessed, I'm Welsh, and true to the traditions of the story-telling bards and druids, I could rattle on forever about things like this.
The point is that Celtic Chelsea Manning is following on with the best traditions of the old Celts by "welshing" on the Anglo-Saxon ruling class.