The Battle of Sinop in 1853 the Black Sea Fleet under Nakhimov made a number of tactical innovations. During the Siege of Sevastopol in 1854–1855, the Russian sailors used all means possible to defend their base from land and sea. In accordance with the Treaty of Paris, Russia lost the right to have a military fleet in the Black Sea. In the 1860s, the Russian fleet which had relied upon sails lost its significance and was gradually replaced by steam.