Sprawa pruska w pokoju oliwskim z 3 maja 1660 r. cz. 3 Uznanie a zwyczaj prawnomiędzynarodowy w praktyce politycznej dotyczącej Prus Ksiażęcych w drugiej połowie XVII w.

The conclusion of peace in Oliwa on May 3, 1660, ending the Northern War begun in 1655, implied an acceptance of the provisions of earlier treaties, including the bilateral Polish–Brandenburg Treaty of Velawy (1657), regulating mutual relations between Prussia and the Republic of Poland. It was particularly important to recognise the legal and political status of Ducal Prussia after 1657. However, due to the limited recognition of the full external independence of the Prussian principality in the Treaty of Velawy, this matter was the subject of Brandenburgian efforts, aimed at strengthening this position. The problem gained special significance in the context of the coronation of Elector Frederick III as king of Prussia, as Frederick I, which in the face of Poland’s weakness was confirmed by international recognition.