Treaty that officially ended the Crimean War. Russia surrendered southern Bessarabia to Moldavia, and surrendered her role as protector of the Christian Shrines in the Ottoman Empire, the putative cause of the war. The Danube was opened to international trade, establishing it as one of the great arteries of world trade, a status it retains to this day, and made the Black Sea neutral, temporarily preventing the Russians from maintaining a war fleet in the Black Sea, the main French and British objective.