They say that the Ukrainian war is returning us to the 1930s. So here is a flash from that past. Behold, gorgeous in full-fig diplomatic uniform with his cocked hat under his arm, the British ambassador to Berlin as he mounts the steps to the foreign ministry in the Wilhelmstrasse. He is carrying a document, Britain’s ultimatum. Confirm Germany’s cessation of hostilities against Poland before 11am or a state of war will exist between us. But it’s only nine in the morning. Nobody much is about. So Sir Nevile Henderson stands on a carpet in the hall by himself and slowly reads the ultimatum aloud. Then he leaves. It’s 3 September 1939. Does Vladimir Putin’s aggression really mean that we must relive those times, when the League of Nations fumbled with endless European crises over minorities and plebiscites and frontiers and land-grabbing invasions? True, states today don’t bother with declarations of war. Hitler and Stalin showed Putin how to dispense with that rubbish and replace it with rubbish proclamations dripping with lies, hypocritical victimology and fake history. But some of those old riddles survive to plague us. One is the difference – if there is one – between “independence” and “territorial integrity”. Liz Truss, as foreign secretary, is among the most hawkish politicians over Ukraine. In her “war aims”, supporting its independence means not only helping to beat away the Russians but restoring Ukraine’s “integrity” – the pre-2014 frontiers that included Crimea and the whole Donbas region. But that’s a dangerous muddle, conflating two things that aren’t the same. (How could the Foreign Office have let her say it?) It also takes us back to that ambassador with his cocked hat. Six months earlier, in March 1939, the prime minister, Neville Chamberlain, had staggered the world (and himself) by reversing his “appeasement” policy; he issued a “guarantee” to Poland that Britain would go to war if Nazi Germany violated Polish independence. Six months later, Hitler did attack Poland. The Nazis seized Danzig, the Wehrmacht tanks poured over the border, the Luftwaffe bombed Warsaw. Britain’s guarantee was triggered. Or was it? As his “peace for our time” hopes collapsed around him, Chamberlain made a last, futile suggestion: Poland’s “independence” was not threatened by the Nazi invasion, only its “territorial integrity” (Hitler was claiming the Danzig region). So perhaps the war didn’t have to happen. This thought earned only contempt. With Hitler, violation of territory and independence came to the same thing. Ukraine, outside Nato, has no “guarantee” of anything. There are three ways this war could end: Russia driven back to the pre-2014 line; Ukraine defeated and partitioned; or (the most likely at present) a stalemate along a fragile ceasefire line. That would leave Russia occupying some territory claimed by Ukraine while peace negotiations dragged on. International arbiters will be tempted to push some obvious compromise: Russia keeps Crimea, while Donbas is partitioned under UN auspices. Too neat to work? First, peacemakers have to answer one brutal question: is Putin Hitler? In other words, will any compromise – leaving him with some conquests – simply encourage plans for further conquests? Remember Munich, in 1938. The Sudeten Germans had a pretty good case, in self-determination terms, for leaving Czechoslovakia and joining Germany. But, as events proved, that case should have been outweighed by the recognition that Hitler was an aggressive monster out to swallow all Europe. Much the same could be said about Crimea. Its population mostly feels Russian and regarded the peninsula’s attachment to Ukraine as, at best, a Soviet-era mistake. But to accept Crimea’s clumsy seizure by Russia as legitimate only encourages Putin’s ambition to annex other fragments of the old Soviet dominion. The trouble is that Truss’s “maximalist” war aims assume independence and territorial integrity are indivisible. They are not. Take Poland. The nation was stripped of many ancient cities and a third of its territory in 1945. But, once free of Soviet imperial overlordship, its independence is intact. The Trianon treaty in 1920 reduced Hungary to less than a third of its prewar size, but left a ferociously independent “core” Hungary. Georgia (like Ukraine, an informal Nato candidate) still insists Abkhazia is integral to its sovereignty, although that tiny Black Sea nation rejected absorption into Georgia in 1993. But no one would dare say that in “losing” Abkhazia Georgia lost its independence. At tomorrow’s Victory Day parade in Moscow, Putin may claim “mission almost accomplished”. That depends on how narrowly he can define “mission”. But peace talks, if and when they begin, will inevitably centre on where new frontiers will run, which means, unfairly, finding out how much lost territory Ukraine will give up. Here danger lurks. Ukrainian politics since independence in 1991 have been unforgiving, to put it mildly. Volodymyr Zelenskiy’s brave and selfless war leadership has been a break with the corrupt oligarchs and demagogues who have mostly hogged the Kyiv stage. But if Zelenskiy takes responsibility for ending the war on a bargain that included, say, accepting that Crimea stays with Russia, some ambitious figures would be tempted to stab him in the back as a betrayer of Ukrainian independence. They could fill the streets with hyper-nationalist mobs and Zelenskiy’s creation – a new degree of national unity – would dissolve in chaos. Hope lies with the younger generations now fighting for their country. Their world view is west of centre: a European Ukraine that is liberal- or social-democratic, a nation where the rule of law and transparency are more than slogans. Some of them are from the west of the country, their identities secure in their Ukrainian language and culture. But the men and women who really matter are the millions who speak Russian, who regard themselves as ethnically Russian but who now, through contempt for Putin’s regime and blazing outrage at this invasion of what is their homeland, have come to feel fully Ukrainian. Their country is in ruins, but it is their country now. Neal Ascherson is a journalist and writer Do you have an opinion on the issues raised in this article? If you would like to submit a letter of up to 300 words to be considered for publication, email it to us at observer.letters@observer.co.uk