It could be summoned either by tsar, or patriarch, or the Boyar Duma. Skopje became the capital of Tsar Stefan Dusan's empire. Bulgaria under Tsar Ivan Aleksandar was expanding and prosperous. The Holy Alliance was the brainchild of Tsar Alexander I. In 1558, tsar Ivan the Terrible invaded Tartu beginning the Livonian War. Feodor was succeeded as tsar by Godunov. Grand Duke Michael married without the permission of the Tsar, Natasha Sergeyevna Wulfert. He was replaced by Vladimir Kononov, who is known by the nom de guerre "Tsar". Some princely titles are derived from those of national rulers, such as tsarevich from tsar. Encouraged by the promise of Tsar Alexander III. The first ruler to adopt the title "tsar" was Simeon I of Bulgaria. Alexander II is still regarded as "The Good Tsar" in Finland. He is deeply attracted by Tsar Alexander's charisma. There is one living former Bulgarian Tsar&colon; Simeon Sakskoburggotski. The visit coincided with the birthday of the Russian Tsar.