century when Christianity was forcibly imposed on the local population. Danish rule of Tallinn and northern Estonia started in 1219. In 1285, Tallinn, then known more widely as Reval, became the northernmost member of the Hanseatic League – a mercantile and military alliance of German-dominated cities in Northern Europe. The king of Denmark sold Reval along with other land possessions in northern Estonia to the Teutonic Knights in 1346. Reval was arguably the most significant medieval port in the Gulf of Finland, the second-most important port being Turku. Reval enjoyed a strategic position at the crossroads of trade between the rest of western Europe and Novgorod and Muscovy in the east. The city, with a population of about 8,000, was very well fortified with city walls and 66 defence towers. A weather vane, the figure of an old warrior called Old Thomas, was put on top of the spire of the Tallinn Town Hall in 1530. Old Thomas later became a popular symbol of the city. In the early years of the Protestant Reformation, the city converted to Lutheranism. In 1561, Reval (Tallinn) became a dominion of Sweden. During the 1700–1721 Great Northern War, plague-stricken Tallinn along with Swedish Estonia and Livonia capitulated to Tsardom of Russia (Muscovy) in 1710, but the local self-government institutions (Magistracy of Reval and Estonian Knighthood) retained their cultural and economical autonomy within Imperial Russia as the Governorate of Estonia. The Magistracy of Reval was abolished in 1889. The 19th century brought industrialisation of the city and the port kept its importance. On 24 February 1918, the Estonian Declaration of Independence was proclaimed in Tallinn. It was followed by Imperial German occupation until the end of World War I in November 1918, after which Tallinn became the capital of independent Estonia. During World War II, Estonia was first occupied by the Soviet army and annexed into the USSR in the summer of 1940, then occupied by Nazi Germany from 1941 to 1944. During the German occupation Tallinn suffered from many instances of aerial bombing by the Soviet air force. During the most destructive Soviet bombing raid on 9–10 March 1944, over a thousand incendiary bombs were dropped on the town, causing widespread fires, killing 757 people, and leaving over 20,000 residents of Tallinn without shelter. After the German retreat in September 1944, the city was occupied again by the Soviet Union. During the 1980 Summer