ANY student of history knows that wars often start as much by accident as by design. Some people want to fight and egg on those who don’t. Preparations start to be put in place, good men and women do not act soon enough to speak against it, and in the end, disaster befalls them all.

I keep thinking of those parallels as I spend more and more of my time working on the many problems that would become acute if there was “no deal” with the EU by March 29 – the date on which the UK will leave unless specific actions are taken to change or cancel Brexit.

There are Tories who are backing a no-deal Brexit inside and outside the UK Government. And although commentators glibly assert that the majority of MPs are against such an outcome, when the matter came to the vote last week, the amendment that narrowly passed was the weakest possible option. The Commons did not back concrete legal action that would have made a no-deal impossible.

On Wednesday, I will further update the Scottish Parliament on Scottish Government preparations in case this scenario is forced upon us. Lots of people are working very hard indeed, but we cannot do everything. So, in addition to preparing, we must raise our voices and speak ever more clearly against such a disaster.

There is no doubt many small businesses are simply not yet focussed on how to survive if normal trading stopped. Nor are many individuals fully aware of the complex supply chains and regulatory arrangements that put food on their table, ensure the medicines they take are available at the doctors or the chemists and underpin normal travel for business and pleasure.

I was at the Port of Zeebrugge in Belgium 10 days ago and one image sticks with me – the sight of a huge tanker sailing in, fully loaded with orange juice from Brazil. Within hours that orange juice had been piped into cartons at a dockside factory and was on its way in containers to supermarkets in Dunoon, Dundee and Dingwall. If there are any delays at customs or a 10-mile queue at Dover, then the supply simply (and literally) dries up.

Yet orange juice is only one commodity. There are thousands more. Meanwhile, our fishermen will not be able to sell their catches (no matter how much bigger an opportunity some of them think they will have), and the normal exporting of goods – food, drink, electronics and other items – will be disrupted.

These expectations are not the work of “Project Fear”. They are sober assessments, and no amount of planning can change completely the dependencies that have built up over 40 years.

Certainly, we could erect an orange juice packing station at Leith, but it would take some considerable time, investment by a multinational and an access to a wider market than the UK. And though time will be there, the other two will not be.

But the worst thing about all this isn’t even the damage, discomfort and perhaps even danger in some cases, that could lie ahead. It is the sheer stupidity and political pigheadedness of those who could stop it happening before it starts.

In fact, some of those people are actually engaged in a monumental deception – an attempt to normalise a no-deal Brexit so that they can achieve the type of hard-line, isolationist, rich man’s exit they salivate over.

The Prime Minister could – and must – rule out a no-deal by immediately requesting an extension to Article 50. She must bring an end to the chaos and uncertainty.

That would be a step away from an imminent crisis. But in the longer term it would not be enough. There needs to be a resolution to the Brexit impasse, which must involve the people themselves – as most of their mainstream politicians have failed them.

And then, in Scotland, we need to take the next, and final, vital step away from Brexit dependence, which can only be done by choosing the normality of independence.