This week will mark the beginning of what will be a defining event in the history of the British State, and all four members of it.
The UK Prime Minister faces the very real prospect that one of those members - Scotland - will demand to leave in order to preserve its membership of another union which the people of both Wales and England voted to leave. She must also deal with the possibility, or even probability, that Northern Ireland will leave and reunite with the Republic of Ireland, enabling it to preserve its membership of the European Union too.
These possibilities and probabilities exist largely because of Westminster's insistence on making Brexit as extreme as possible - cutting all economic and social ties with the continent regardless of the impact on people's lives in the British Isles.
Both Scotland and Wales, through their respective governments, have pointed out the crucial importance of their respective trade links with Europe and the need to maintain their membership of the Single Market and the Customs Union in order to preserve those links. Those calls have been ruled out by Theresa May, despite their value and importance to three of the four countries she represents as the UK Prime Minister, and despite her repeated assertions that she will listen to all the nations in the Union, not just her own.
The SNP, to their credit, have repeatedly told Westminster that if Scotland retained its membership of the Single Market after Brexit, they wouldn't block it, despite the people of Scotland voting overwhelmingly to remain a full member of the European Union. It is Theresa May's insistence on ignoring the interests of Scotland, as well as Wales and Northern Ireland, in pursuing the most extreme form of Brexit possible and refusing to negotiate with the nations that has led her to this position. The empty rhetoric about the UK being a partnership of equals no longer holds sway.
The comprehensive, sensible and moderate proposals put forward by both the Welsh and Scottish Governments contrast starkly with Westminster's blind faith approach, with no plan and no White Paper. It is as if Ministers believe that as long as they have their Union Jack safety blanket draped over them, everything will be fine.
Triggering Article 50 this week with no plan and no agreed UK-wide position will probably go down in history as one of the most devastating acts of negligence since the Crimean Board of Inquiry laid bare the same lethal cocktail of vanity and incompetence that we came to know as the 'Charge of the Light Brigade'.
The first hurdle will be the divorce bill to cover the UK's liabilities once it leaves, which the EU has priced at £50 billion. The hard-right Brexiteers are already using this as an excuse to leave the EU with no deal, leading to a cliff-edge effect in going from complete free trade with the Single Market and the 53 other countries with whom the Customs Union as a trade deal, to having no trade deals at all, putting serious pressure on businesses.
As a country with an economy that heavily relies on exports, the majority of which go to the Single Market, this would be catastrophic for Wales. Plaid Cymru's preference, and the preference of the Welsh Government, is continued membership of the Single Market and Customs Union after Brexit. A Free Trade Agreement with the Single Market pales in comparison to membership but it would be far, far better than the cliff-edge option advocated by the hard-right.
That Theresa May refuses to take the clear needs of the other nations into account shows clearly that Brexit is a Westminster project and that the UK is certainly not a partnership of equals.
Despite being the Prime Minister for all parts of the British State, Theresa May did not inform Wales, Scotland or Northern Ireland of Westminster's 12-point Brexit plan or their White Paper, let alone consult with them. Despite there being a Joint Ministerial Committee set up to allow cross-parliamentary talks, the devolved nations all found out that Article 50 would be triggered this week through the BBC. As a Welsh Government Minister said in an evidence session on the Brexit Select Committee, community councils are more professional than the Joint Ministerial Committee.
Never before has there been a political process that highlights the powerlessness of our democratic national government in Wales as Brexit is doing. Wales has long been ignored in this union but the impact has, so far, been piece by piece, always just about minor enough not to catch attention. But now the shackles on our nation are as clear as ever.
Our Labour First Minister himself knows the game is up. From my experience of Westminster, those most opposed to giving Wales any notice whatsoever are Labour MPs, and the First Minister's plea for his party to urgently discuss the future of their own devolution policy read like a Garrison Officer phoning central command and asking for reinforcements before the natives take over.
The problem for the British State, as it heads towards the triggering of isolationism, is that the whole is far less than the sum of its parts. The people of Scotland are awake to this fact, and unless Theresa May changes her approach, it will only be a matter of time before the people of Wales begin to wonder: would we not be better off if we began governing ourselves?