Constantin Pavlovich was the second son of Tsar Paul I Petrovich and Sophia Dorothea Augusta Louisa of Württemberg. Grand Prince Constantin most resembled his father, both physically and mentally. He had a passion for all things military. However, his unpredictability of behavior and his tendency towards rude and insulting behavior towards his young wife, Anna Fyodorovna, were also characteristic of his personality. His older brother Alexander is now the tsar of Russia.