Constantine (Konstantin Pavlovich)kənstəntyēnˈ pävˈləvĭch, 1779–1831, Russian grand duke, second son of Czar Paul I and brother of Alexander I and Nicholas I. On the death of Alexander I (1825), Constantine was next in line for succession to the throne. However, in 1822 he had secretly renounced his claim in favor of Nicholas in return for Alexander's permission to divorce his first wife and marry a Polish countess. The arrangement was not made public and some confusion resulted concerning the succession. A group known as the Decembrists took advantage of the situation and attempted to seize power under the slogan "Constantine and Constitution." Nicholas quelled the uprising. During the entire episode Constantine remained in Poland, where he had been commander in chief and virtual governor since 1815. The severity of his administration there led to the Polish uprising of 1830. Constantine died before the rebellion was suppressed.