Karl von Diebitsch launches the Transbalkan offensive, which brings the Russian army within 68 km of Istanbul. September 16, 1829 – Russo-Turkish War, 1828–1829: The Treaty of Adrianople gains for Russia some territory at the mouth of the Danube and along the eastern coast of the Black Sea. Northern Europe February 3, 1825 – Vendsyssel-Thy, once part of the Jutland peninsula that formed westernmost Denmark, becomes an island after a flood drowns its 1 km wide isthmus. September 27, 1825 - The world's first modern railway, the Stockton and Darlington Railway, opens with engineer George Stephenson driving the first public train pulled by the steam engine Locomotion No 1. September 4, 1827 – Finland: The Great Fire of Turku destroys 3/4 of the city, with many human casualties. Central Europe October 25, 1820 –November 20 – The Congress of Troppau (Opava) is convened between the rulers of Russia, Austria and Prussia. October–December, 1822 – Congress of Verona: Russia, Austria and Prussia approve French intervention in Spain. July 6, 1825 – The Duke of Schleswig-Holstein-Sonderburg-Beck gains possession of Glücksburg and changes his title to Friedrich Wilhelm, Duke of Schleswig-Holstein-Sonderburg-Glücksburg. The line of Schleswig-Holstein-Sonderburg-Glücksburg later becomes the royal house of Greece, Denmark and Norway. Southern Europe January 1, 1820 – A constitutionalist military insurrection at Cádiz leads to the summoning of the Spanish Parliament (March 7) (see Mid-nineteenth century Spain). March 9, 1820 – King Ferdinand VII of Spain accepts the new constitution, beginning the Liberal Triennium ("Trienio Liberal"). July 1820 – A Constitutionalist revolution occurs in the Kingdom of the Two Sicilies. August 24, 1820 – A Constitutionalist insurrection breaks out at Oporto, Portugal. September 15, 1820 – A revolution breaks out in Lisbon (see Portugal's crises of the Nineteenth Century). September 22, 1822 – Portugal approves its first Constitution. January 4, 1825 – King Ferdinand I of the Two Sicilies is succeeded by his son Francis I of the Two Sicilies. May 28, 1826 – Pedro I of Brazil abdicates as King of Portugal. June 23, 1828 – Portugal: King Miguel I overthrows his niece Queen Maria II, beginning the Liberal Wars. Greek War of Independence At the start of the decade, most of Greece was under the rule of the Ottoman Empire, as it had been since 1453, despite frequent revolts. In early 1821, a secret organization called the Filiki Eteria instigated several battles that, together with the blessing