Konstantin Pavlovitsj was a grand duke of Russia and the second son of Emperor Paul I and Sophie Dorothea of Württemberg. He was the Tsesarevich of Russia throughout the reign of his elder brother Alexander I, but had secretly renounced his claim to the throne in 1823. For 25 days after the death of Alexander I, from 19 November (O.S.)/1 December 1825 to 14 December (O.S.)/26 December 1825 he was known as His Imperial Majesty Konstantin I Emperor and Autocrat of All the Russias, although he never reigned and never acceded to the throne. The succession controversy became the immediate cause of the Decembrist revolt.