Alexis (Aleksey Mikhailovich), 1629-76, czar of Russia (1645-76), son and successor of Michael. His reign, marked by numerous popular outbreaks, was crucial for the later development of Russia. A new code of laws was promulgated in 1648 and remained in effect until the early 19th cent.; it favored the middle classes and the landowners, but tied the peasants to the soil. The reforms of Patriarch Nikon resulted in a dangerous schism in the Russian Church, and Nikon's deposition (1666) was a prelude to the abolition of the Moscow patriarchate in 1721. In 1654 the Cossacks of Ukraine, led in revolt against Poland by Bohdan Chmielnicki, voted for the union of Ukraine with Russia. War with Poland ensued and ended in 1667 with Russia retaining most of Ukraine. A serious revolt against the czar (1670) among the Don Cossacks under Stenka Razin was quelled by 1671. Alexis was succeeded by his son Feodor III. A younger son, by a second marriage, became Peter I (Peter the Great).