Nicholas I (6 July [O.S. 25 June] 1796 – 2 March [O.S. 18 February] 1855) was Emperor of Russia, King of Congress Poland, and Grand Duke of Finland from 1825 to 1855. He was the third son of Paul I and younger brother of his predecessor, Alexander I. Nicholas's thirty-year reign began with the failed Decembrist revolt. He is mainly remembered as a reactionary whose controversial reign was marked by geographical expansion, centralisation of administrative policies, and repression of dissent both in Russia and among its neighbors. Nicholas had a happy marriage that produced a large family, with all of their seven children surviving childhood.
Nicholas's biographer Nicholas V. Riasanovsky said that he displayed determination, singleness of purpose, and an iron will, along with a powerful sense of duty and a dedication to very hard work. He saw himself as a soldier—a junior officer consumed by spit and polish. A handsome man, he was highly nervous and aggressive. Trained as a military engineer, he was a stickler for minute detail. In his public persona, stated Riasanovsky, "Nicholas I came to represent autocracy personified: infinitely majestic, determined and powerful, hard as stone, and relentless as fate."