Radziwill was Governor of the Duchy of Prussia (Brandenburg-Prussia) (generalny gubernator Prus Książęcych) since 1657.
After the secularization of the Teutonic Knights in 1525 the village became part of the Duchy of Prussia and the Kingdom of Prussia in 1701.
The first synagogue was a chapel built in 1680 in Burgfreiheit (a location which was a ducal Prussian immunity district around the castle, not administrated by the city).
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In 1587, the diocese was secularized by the regent of Ducal Prussia, George Frederick.
The Hohenzollerns expanded their territory by acquiring the Duchy of Prussia in 1618, the Duchy of Cleves (1614) in the Rhineland, and territories in Westphalia.
George Frederick (1539–1603), who became Margrave of Brandenburg-Ansbach and Regent of the Duchy of Prussia.
As a gratification for his diplomatical achievements Frederick William presented to him in 1653 the manor of Eichmedien (Nakomiady) in Masuria, Duchy of Prussia.
Upon the death of his kinsman Albert I, Duke of Prussia in 1568, the Duchy of Prussia was inherited by the latter's underage son Albert Frederick.
Marie of Prussia (23 January 1579 - 21 February 1649) was a Prussian princess by birth and Margravine of Brandenburg-Bayreuth by marriage.
In the course of the Protestant Reformation, the Teutonic State in 1525 dissolved and the Nemirseta area became the northernmost outpost of secularized Duchy of Prussia, from 1618 of united Brandenburg-Prussia under the Lutheran House of Hohenzollern.
Congruent with the Kingdom of Prussia proper (i.e. former Ducal and Royal Prussia), its territory, like the Greater Polish territory of Posen, was not part of the German Confederation.
The black eagle was later adopted when the Teutonic State was transformed into the Duchy of Prussia in 1525.
On July 29, 1657 they signed the Treaty of Wehlau in Wehlau (Polish: Welawa; now Znamensk), whereby Frederick William renounced a previous Swedish-Prussian alliance and John Casimir recognised Frederick William's full sovereignty over the Duchy of Prussia.
It appears that Andrzej Jr. was born while his father Benedykt Wiszowaty was a Unitarian minister in Kosinowo, in the Duchy of Prussia.