In what year did the Great Northern War, between Russia and Sweden, end?

The story behind the answer

1721 is correct because the Great Northern War (1700–1721) formally ended with the Treaty of Nystad, which concluded hostilities between Russia and Sweden. That treaty ceded key Baltic territories—Ingria, Estonia, and Livonia—to Russia, giving it vital access to the Baltic Sea and marking the decline of Sweden as a great power.

The outcome reshaped Northern Europe: Peter the Great used this victory to proclaim the Russian Empire in 1721 and elevate St. Petersburg—founded in 1703—as his “window to the West.” To remember the date, link it to Russia’s “coming of age”: 1700 to 1721, and the “21” as the year Peter takes the imperial title and Russia steps onto the European stage.