When the Seven Years' War broke out (1757), Russian troops defeated the Prussians near Königsberg and occupied all of Prussia.

An excerpt from the article 24 facts about Kaliningrad

Tsarina Elizabeth (younger daughter of Peter I the Great and his second wife, Empress Catherine I) incorporated the Kingdom of Prussia along with Königsberg into Russia. The castle in Königsberg became the seat of the Russian governor.

Immanuel Kant, born in Königsberg, submitted, among others, an oath of allegiance to Tsarina Elizabeth.

The death of Tsarina Elizabeth (the so-called miracle of the House of Brandenburg) resulted in the restoration of power in Prussia to the Hohenzollerns. The Russians withdrew from Königsberg in 1763.

In 1871, the city became part of the newly established German Empire.