May 26, 1648: Cossack forces led by Bohdan Khmelnytsky defeat Polish units at Korsun. May 26, 1926: Ukrainian ОmigrО leader Simon Petliura is assassinated in Paris. May 27, 1657: the Holy Roman Empire enters an alliance with the Polish Kingdom and undertakes to provide military assistance. May 27, 1703: St. Petersburg is founded in Russia. May 28, 1812: Russia and Turkey sign the Peace Treaty of Bucharest. May 28, 1957: the first republican youth festival ends in Kyiv. May 29, 1922: the Council of People’s Commissars of the Ukrainian SSR passes a decree on protection of ornamental gardening and forest belts in Ukraine. May 29, 1964: the USSR’s largest botanical gardens open in Kyiv. May 30, 1876: the tsarist Russian government issues the Ems Ukase banning book publishing in Ukrainian. May 30, 1923: a Ukrainian Historical-Philological Society is founded in Prague. May 31: Smoke Out Day (initiated by the World Health Organization). May 31, 1924: the Council of People’s Commissars of the Ukrainian SSR adopts a resolution protecting the Ancient Greek city of Olbia. June 1: International Children’s Day. June 1, 1967: the millionth diesel engine comes off the main conveyor line of Kharkiv’s Hammer and Sickle Works.