Prince Krzysztof Radziwià Âà  (; 22 March 1585 â 19 November 1640) was a PolishâÂÂLithuanian noble (szlachcic), magnate, politician and military commander of his epoch. Sometimes referred to as Krzysztof Radziwià Âà  II, to distinguish him from his father, Krzysztof "Piorun" Radziwià Âà Â.
Owner of Birà ¾ai, he was Field Lithuanian Hetman from 1615, Castellan of Vilnius from 1633, Voivode of Vilnius from 1633. Grand Lithuanian Hetman from 1635, starost of Mogilev, Bystrzyca, à ½ieà ¾mariai and Seje. In 1632 he served as Marshal of the Sejm.
He successfully fought in Livonia against Sweden from 1600s to 1617. He took part in the campaign against the Swedes in the Baltic region in 1621âÂÂ1622 (Polish-Swedish War), where he agreed to a controversial truce (as he had no permission to negotiate it from the king or the Sejm). Important commander of the Grand Ducal Lithuanian Army during the Smolensk War, where he was instrumental in obtaining the capitulation of the Russian army in the relief of Smolensk. Afterwards, in 1635, he retired from his military career, concentrating on administering his estates. A Calvinist, he was a great protector of Protestants in Lithuania.
He was an opponent of Catholic king Sigismund III Vasa, but a supporter of his more tolerant son, Wà Âadysà Âaw IV. An advocate of Wà Âadysà Âaw's marriage to a Protestant princess, he distanced himself from the king after Wà Âadysà Âaw declined this marriage proposal. He opposed an alliance between the Commonwealth and the Habsburgs. On his lands in KÃÂdainiai he founded a major Calvinist cultural and religious centre, which flourished till the 19th century as a center of the Lithuanian Reformed Church. His large horse stables were famous throughout Europe.
Radziwià Âà  collected various curiosities at the Lubcha Castle: minerals, mollusc shells, corals, hunting trophies, whale bones, elephant tusk, nut shells, and similar items. It is believed that at least three items (moose horn collection, a chair made of horns, and a jaw bone of bowhead whale) of the collection are preserved at the Zoological Museum of Vilnius University.