Question: Marcin Kromer, was Prince-Bishop of Warmia (Ermland), a Polish cartographer, diplomat and historian in the Kingdom of Poland and later in the Polish-Lithuanian Commonwealth, he was a personal secretary to two Kings of Poland, Sigismund II Augustus and Sigismund I of Poland, of the Jagiellon dynasty, reigned as King of Poland and also as the Grand Duke of Lithuania, during which time span?
Sentence (from "Barbara Radziwiłł"): Sigismund Augustus, assisted by Barbara's cousin Mikołaj "the Black" Radziwiłł and brother Mikołaj "the Red" Radziwiłł, worked tirelessly to gain recognition of their marriage and to crown Barbara as Queen of Poland.
Relevant evidence: No