Together with his brother Jan, Koźmian took part in the November Uprising. On November 30, 1830 he joined the and fought in the honour guard of the commander of the Polish army, Józef Chłopicki. He took part in the Battle of Olszynka Grochowska on February 25, 1831. With his old friend from school he edited the newspaper "Dziennik Gwardii Honorowej", and translated Goethe's "Clavigo" and Schiller's "William Tell". During the uprising, Koźmian wrote patriotic poems; his "War Song" ("") was performed to the tune of "God Save the King".