The book ends with a meeting between the pigs and the neighboring humans. The animals watch on through a farmhouse window as the pigs explain that there must have been some misunderstanding. They want to make it clear to the humans that they never meant to incite rebellion; their entire goal has been "to live at peace and in normal business relations" (10.27, our italics). In short, the pigs have hung the other animals out to dry – the Rebellion is dead.
The meeting between the pigs and the humans is an allusion to the Tehran Conference, which took place in November of 1943, and which was intended to map out a strategy to end World War II. It was a meeting of the leaders of the Big Three allied powers, jointly leading the fight against Hitler: Franklin Roosevelt of the United States; Winston Churchill of the United Kingdom; and Joseph Stalin of the Union of Soviet Socialist Republics (U.S.S.R.).
At the Tehran Conference, the Big Three hammered out agreements on several matters of great significance to World War II and, later, the Cold War. Stalin, whose soldiers on the Eastern Front were bearing the brunt of the war against Germany, got Churchill and Roosevelt to promise to open up a Western Front in France by the spring of 1944 by finally launching Operation Overlord (now known as D-Day). (Stalin had been begging since 1941 for the British and Americans to open a Western front to take the pressure off his forces.) Churchill and Roosevelt also agreed, reluctantly, to allow Stalin to permanently change the borders of Poland, incorporating much of what had been eastern Poland into the Soviet Union. Many in the West (the Polish government-in-exile in London foremost among them) saw this as a craven sellout of democratic principles… which it may have been. But it was a sellout that Churchill and Roosevelt saw as necessary to win the war.
But it was also a sellout that drew the ire of George Orwell. What people often emphasize when they read the end of Animal Farm is that the pigs have become exactly like the humans. The final line goes, "The creatures outside looked from pig to man, and from man to pig, and from pig to man again; but already it was impossible to say which was which" (10.32).
In the Preface to the Ukrainian edition, Orwell emphasizes this note of discord at the end of the novel. Though the creatures cannot tell pig from man, as they observe them, the pigs and the men are caught in ferocious argument. The reason is that they’re both cheating one another: "Napoleon and Mr. Pilkington had each played an ace of spades simultaneously" (10.32).
The end of Animal Farm, the moment when that ace of spades hits the table, might be taken as the allegorical beginning of the Cold War. At the time the West decided to play cards with the Soviet Union; they’d do anything to defeat the Germans. But the wartime alliance of Roosevelt and Churchill and Stalin was a temporary marriage of convenience; as soon as the war ended, it fell apart in a mess of mutual distrust, leading directly to fifty years of stalemate, to fifty years of such incredible tension between Russia and the West that schoolchildren in both countries were drilled on what to do if a nuclear bomb landed nearby. Orwell, it seems, saw it coming a mile away.