[5] He read and wrote in both Polish and Ruthenian, although his handwritten letters are written in illegible and careless handwriting, indicating the magnate's low level of calligraphy.

[14] Under King Stephen Báthory, he was fairly successful in defending the eastern borders of the Grand Duchy of Lithuania against the Muscovy.

[2]His political career was marked by his alliance with his cousin Mikołaj "the Black" Radziwiłł with whom he opposed the other notable Lithuanian families in the rivalry for the dominant status in the Great Duchy.

The alliance marked the formation of a dynastic-like cooperation between Radziwiłłs and showed how family interests could affect magnates relations with the Commonwealth.

[2] He was one of the most prominent converts and advocates of Protestantism in Polish–Lithuanian Commonwealth and his line of the family became devoted members and defenders of the Lithuanian Evangelical Reformed Church until its extinction.