Allies at war: The politics of defeating Hitler by Tim Bouverie (Bodley Head £25, 672pp)
IN MANY cases, Donald 'Mr Tariff' Trump is fond of saying, as he justifies his vendetta against nations who have allegedly been ripping America off for years, 'the friend is worse than the foe'.
He speaks as if this is an insight that has eluded mankind until now, one that only he, in his infinite, unprecedented wisdom, has come to realise and reveal to an astonished world.
Well, not quite, Mr President.
Virgil was saying pretty much the same thing a couple of millennia ago when he warned, 'Beware of Greeks bearing gifts'. And more recently - as this terrific new book, Allies At War, by Tim Bouverie, shows in great and glorious detail - in the Second World War negotiating your way through the shifting diplomatic quicksand imposed by friends and allies was almost harder than actually confronting the enemy.
At least you could be sure which side Hitler was on - though the same could not always be said for the likes of the wily, poker-faced Stalin, the truculent, disruptive De Gaulle and numerous other leaders.
Behind a united front lurked lies, secrets, suspicions and spats.
Though Churchill knew the score. 'There is only one thing worse than fighting with allies,' he opined, 'and that is fighting without them.' But he himself was far from averse to a bit of manipulation and double-dealing when it suited him.
Nor was his relationship with US president Roosevelt as smooth and straightforward a love-in as the 'special relationship' - the phrase Churchill coined for transatlantic co-operation (but only after the war) - suggested.
It was fundamentally unequal, more, as Bouverie suggests, a 'pleading relationship'.
It still is: witness Keir Starmer’s sucking-up in the White House, and that cringe-making handover of a letter from the King.
And while Americans are right in their belief that the US twice went to war in Europe to bail us out - both first and second World Wars would have had a different outcome without them, for which we are grateful - they struck a hard financial bargain in return in the form of a multi-billion dollar loan that was not paid off until the 21st century.
Even when Roosevelt appeared to be outstandingly generous and altruistic, if you burrow into the detail there is often a catch.
As in 1940 (before the US actually joined the war) when, amid plenty of self-congratulation, Roosevelt donated 50 destroyers to the Royal Navy.
Unfortunately, as a less than grateful British admiral pointed out, they were old rust-buckets; they leaked and their engines were defective. All in all, pretty useless.
Yet in return, the US got a number of bases on British islands in the Caribbean, leading a British Cabinet member to accuse the US of 'unseemly greed'.
Buried here is another truth about the 'special relationship': that although Churchill and Roosevelt were eager bedfellows with much mutual respect between one another, the hierarchies of military and ministers below them on both sides were often marked by suspicion and even outright hostility.
The Brits distrusted the brash Yanks as vulgar and idle; the Yanks distrusted the snooty Limeys who were, in the words of one US senator, 'a bunch of cunning and scheming brutes'. Differences going back to the American Revolution a century and a half earlier still rankled.
And however much the prime minister and president papered over the cracks in public, there was no getting away from the fact that they had major, potentially deal-breaking differences.
Roosevelt loathed colonialism and wanted the British Empire gone. He feared - rightly - that Churchill was desperate to preserve it.
The fact that after the war anti-imperialist US would be intent on building up an empire of its own (and again still is: see Trump's designs on Canada and Greenland) is one of modern history's ironies/hypocrisies.
It's an irony too that defeating one dictator meant jumping into bed with another and also turning a blind eye to a regime that was on a par with Hitler's in its fanaticism and disregard for human life.
Stalin, Roosevelt, Churchill - not a natural threesome. The stresses and strains between them were many and frequent. After the Germans invaded Russia and reached as far as the outskirts of Moscow and Stalingrad (now Volgograd), the two Western allies were nagged constantly (and not unreasonably) by Stalin to take some of the pressure off him in the East by launching an invasion of Europe from their side.
Churchill’s most significant diplomatic achievement was to stall until the summer of 1944, fearing that a premature invasion across the Channel would end in a bloodbath and defeat.
In the end though, Stalin was the winner in the political jostling. He worked hard on Roosevelt who, as the war came to an end, let himself be so mesmerised by the Soviet leader that he made the mistake of trusting him and assisting in the carve-up of eastern Europe and the Balkans. Churchill was sceptical, conscious of Stalin’s real agenda but realised there was little he could do to save any of those countries forced into the Soviet sphere.
The Big Three: The three leaders discussed the establishment of the Eastern Front at the Tehran Conference
We'd gone to war once before over Poland. It wasn't going to happen again. Churchill had to bite the bullet: there was a new world order, in which Britain was the also-ran, a 'poor little donkey', as he put it, beside the 'big Russian bear' and the 'great American elephant'.
Bouverie is a historian with an exceptional command of his subject, and there is much to learn from his book.
Trump could well do with it on his list of required reading (if there is such a thing) as he turns today's world upside down. It might show him how to do diplomacy - and more importantly how not to do it.
The way Stalin out-manoeuvred Roosevelt might persuade Trump not to trust Putin. And above all, to beware of Russians bearing gifts.