Ducal Prussia held as a fief of Poland until the treaty of
Wehlau
(19 Sep 1657). Elector Friedrich III assumed the title of "king in
Prussia", assured to him by the treaty of 16 Nov 1700 with the Emperor,
on 15 Jan 1701, and was crowned as king Friedrich I on 18 Jan 1701 in
Koenigsberg. The title was recognized by France and Spain at the treaty
of Utrecht in 1713. The Holy See did not recognize
the title until the 19th century. After the first partition of Poland
(treaty
of 18 Sept. 1773) which gave Frederic the Great "royal Prussia" (the
part of Prussia hitherto in
the kingdom of Poland), his title was changed from "king in Prussia" to
"king of
Prussia".