Constantine Nirolayevitch, grand duke of Russia, second son and fourth child of the emperor Nicholas, born in St. Petersburg, Sept. 21, 1827. He was made grand admiral when a mere child, and carefully educated for the navy. He visited Constantinople in 1845, and two years later made a voyage from Archangel to the Mediterranean, visiting several European cities during his absence. In September, 1848, he married Alexandra, daughter of the duke of Saxe-Altenburg. In the following year he accompanied Paskevitch in the Hungarian campaign. During the Crimean war he commanded the fleet of the Baltic in conjunction with Lutke. Being acknowledged leader of the old Russian party in opposition to the progressive views of his elder brother Alexander, his father required him to take an oath of fidelity to the heir apparent. Alexander, on his accession in 1855, placed him at the head of the ministry of the marine. He was charged with the execution of the decree which emancipated the serfs, and was made lieutenant general in Poland during the political agitations which resulted in the insurrection of 1863. In January, 1865, he became president of the council of the empire.