Pick a date in the Second World War and you can usually see the war moving. Pick 1 June 1941 and you get something rarer: a pause. Germany and its partners controlled or dominated more of Europe on that day than on any other, and there was almost nothing left in Europe to fight. Britain was unreachable across the Channel. Everything else was occupied, allied, or officially neutral. Three weeks later Hitler invaded the Soviet Union and the pause ended forever.

The map is worth reading slowly, because it is not simply a map of German conquest.

Start with the black. Germany proper had absorbed Austria, the Sudetenland, western Poland and Alsace-Lorraine outright. Around it sits a grey belt of occupation — Norway, Denmark, the Netherlands, Belgium, northern and western France, the Protectorate of Bohemia and Moravia, and the rump of Poland administered as the General Government. Vichy France holds the south, nominally sovereign, its fleet intact and its empire still under its own flag.

Then look at how much of the map is neither German nor at war with Germany. Sweden, Switzerland, Spain, Portugal, Ireland and Turkey are all neutral in June 1941, and each was neutral in a different way. Sweden sold Germany iron ore and, within weeks of this snapshot, let a fully armed German division cross its territory from Norway to Finland. Spain had declined at Hendaye in October 1940 to enter the war on German terms, then sent a volunteer division east once Barbarossa began. Turkey signed a treaty of friendship with Germany on 18 June 1941 — four days before the invasion, and almost certainly because Berlin wanted its southern flank quiet. Neutrality on this map means unoccupied, not uninvolved.

The Balkans had been settled only weeks earlier, and violently. Yugoslavia was invaded on 6 April and capitulated in eleven days; Greece fell by late April; the Independent State of Croatia was proclaimed on 10 April as a German-Italian client. Crete was taken by airborne assault between 20 May and 1 June, which means the map's own date is the day that campaign concluded. Hungary, Romania, Slovakia and Bulgaria had all joined the Tripartite Pact and appear as allies rather than occupied territory. Romania mattered most: the Ploiești oilfields were the largest source of crude available to the German war economy, and protecting them shaped German strategy in the region thereafter.

Which brings us to the largest single feature on the map. In June 1941 the Soviet Union was not an enemy. It was a partner, and a lucrative one. The Molotov-Ribbentrop Pact of August 1939 had divided Eastern Europe between them, and the commercial agreements that followed made the USSR one of Germany's most important suppliers of grain, oil, manganese and rubber transshipped from Asia. Soviet freight trains were still crossing the demarcation line into German-held Poland in the days before the invasion. Stalin had received repeated warnings — from British intelligence, from his own agents in Tokyo and Berlin — and treated most of them as British provocations designed to start exactly the war they described.

He had reasons for the misjudgement beyond stubbornness. Germany was still at war with Britain, and opening a second front while the first remained unresolved was precisely the error German staff officers had spent twenty years vowing never to repeat. The Red Army's officer corps had also been gutted by the purges of 1937-38, and the Soviet border had moved several hundred kilometres west since 1939, into territory whose defences were unfinished.

At dawn on 22 June, roughly three million Axis troops crossed that border along a front of some 2,900 kilometres — still the largest invasion ever mounted. Finland entered days later to recover what it had lost in the Winter War, which is why the map's north matters. Within six months the German army was outside Moscow, had suffered its first strategic defeat, and the war had acquired the eastern dimension in which most of its European fighting and dying would occur.

The reason 1 June 1941 is worth stopping on is that the map is at its most misleading precisely when it looks most complete. Germany dominated the continent and had run out of things the continent could give it. It could not reach Britain, it could not out-produce the Empire and the United States, and its oil position was thin. Barbarossa was not opportunism on top of success. It was the plan the successes had been clearing the ground for since 1925, and it was launched from a position that looked, on paper, unassailable.

Three weeks after this map, the Axis was at its territorial peak in Europe. It would never look this good again.

Sources: David Stahel, Operation Barbarossa and Germany's Defeat in the East; Richard Overy, Russia's War; Gabriel Gorodetsky, Grand Delusion: Stalin and the German Invasion of Russia; Edward Ericson, Feeding the German Eagle: Soviet Economic Aid to Nazi Germany, 1933-1941; Antony Beevor, Crete: The Battle and the Resistance; Christian Leitz, Nazi Germany and Neutral Europe During the Second World War; US Holocaust Memorial Museum, Holocaust Encyclopedia, "Invasion of the Soviet Union, June 1941."

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