In 1454, the city was incorporated into Poland for a year thanks to King Casimir IV Jagiellon who changed its name to Królewiec.

An excerpt from the article 24 facts about Kaliningrad

Casimir IV Jagiellon created the Królewiec Voivodeship, the capital of which was Królewiec. The first and only voivode of Królewiec was a Prussian nobleman, Ścibor Bażyński.

On April 12, 1455, the city was recaptured by the Teutonic Knights, and the Królewiec Voivodeship ceased to exist.

During the Thirteen Years' War from 1457, Królewiec was the seat of the Grand Master of the Teutonic Knights, who moved here from Malbork Castle.