How was Bjørnstjerne Bjørnson awarded the Noble Prize in Literature?

Name: Bjørnstjerne Bjørnson.
Real Name: Bjørnstjerne Martinius Bjørnson.
Date of Birth: December 8,1832.
Birth Place: Kvikne, Norway.
Died: April 26, 1910.
Death Place: Paris, France
Nationality: Norwegian.
Education: University of Oslo.
Notable Works: The Bankrupt.
Popularly Known: As one of “the four great ones” of 19th-century Norwegian literature.
Noble Prize Year: Nobel Prize for Peace in 1903, for as a tribute to his noble, magnificent and versatile poetry, which has always been distinguished by both the freshness of its inspiration and the rare purity of its spirit.