ause in his opinion it would be too expensive to maintain two courts. James asks Frederick for advice on where he might travel, how long he might stay, and how he should act in case the truce between Sweden and Poland-Lithuania were not extended and war should break out again.
13. Announcement by the delegates of the Sejm and senators of Poland-Lithuania. Warsaw, 16 July 1632. Copy. LVVA, Collection 554, Inventory 3, File 27.
Sigismund III of Poland, who had for many years been hostile towards Duke William, died in April 1632. The members of the Radziwiłł family, related to the Dukes of Courland, managed to convince the delegates of the Sejm, convened in order to elect the new king, to recognise William's right to the throne of Courland. The announcement states that, on the request of the kings of France and England and other rulers, and in recognition of the merits of the house of the Dukes of Courland, the Sejm and Senate is restoring the previous rights of William and his son James, and promises to achieve the agreement of the new king. Władysław IV, who came to the throne in November 1632, accepted this, with the proviso that William was never to return to Courland.
14. Act of agreement between Duke Frederick and James. Mitau/Jelgava, 19 July 1638. LVVA, Collection 554, Inventory 3, File 27.
In 1637 the brother of the King of Poland put forward a claim to Courland. Then Duke Frederick declared that he was transferring the duchy to James, and also obtained the agreement of the Sejm of Poland-Lithuania, which was opposed to any increase in the king's power. However, under the agreement between the two dukes, Frederick would continue to rule as long as he was able. Meanwhile, James also received possession of manors of Goldingen/Kuldīga, Sahten/Sāti, Irmlau/Irlava, Schwarden/Zvārde, Sessau/Sesava and the harbour of Windau/Ventspils.
15. Account of the investiture ceremony of Duke James. Vilnius, 16 February 1639. LVVA, Collection 554, Inventory 3, File 27.
In Vilnius in February 1639 James received his diploma of investiture from Władysław IV, King of Poland, and in a solemn ceremony in Vilnius Castle gave an oath of allegiance to the king. The description of the ceremony is not particularly detailed, mainly listing the persons present. The ceremony was followed by an official dinner, at which the duke sat between the king and the queen. In Vilnius, James also had to sign a promise to build Catholic churches in Mitau/Jelgava and Goldingen/Kuldīga.