This article discusses letters written by King John I Albert to the Grand Masters of the Teutonic Order and other recipients, preserved in the archives of the Teutonic Order. The first of these was sent by the prince, who sought the support of Grand Master Johann von Tiefen during the election of 1492. Most of the correspondence concerns the king’s relations with Tiefen’s successor, Duke Frederick of Saxony. The first problem was Frederick’s refusal to swear an oath of allegiance, which he consistently refused to do. The second important issue was the fight against the Turks, with the king demanding help from the Teutonic Order. The Grand Master’s brother, Duke Georg of Saxony, whose wife was the Polish king’s sister Barbara, was also involved in Polish diplomatic activities. Thirteen letters from the short reign of John Albrecht (1492–1501) were discussed, including their subject matter, form, and accompanying seals.