Peter I (or Peter the Great)
Tsar of Russia (1682–1725). After the death of his half-brother Ivan in 1696 Peter I assumed sole authority and launched a policy of expansion along the Baltic coast. Modernizing his armed forces he waged the Great Northern War (1700–21) against Charles XII of Sweden, and went on to annex Estonia and Latvia, as well as parts of Finland, following the defeat of the Swedish monarch. Peter I's introduction of extensive government and administration reforms were instrumental in transforming Russia into a significant European power. In 1703 he made St Petersburg his capital.