The fierce fighting on the Crimean Peninsula -- and particularly around the strategic port city of Sevastopol -- is one of the most dramatic and impressive pages of the Soviet Union's struggle during World War II. The story highlights the courage and endurance of the Red Army and Soviet civilians. And the Crimean campaign was one of the only bright spots for the Soviet Union during the dark, desperate days of the first two years of the war. In May 1945, Soviet leader Josef Stalin named Sevastopol -- together with Leningrad, Stalingrad, and Odesa -- as the first four "hero cities" of the Soviet Union. Crimea was conquered by the Russian Empire in the 18th century. For most of the Soviet period, it was part of the Russian republic. However, in 1954, the Soviet government transferred it to the Ukrainian republic. After the collapse of the Soviet Union, Russia and the international community agreed to retain Crimea within the borders of the newly independent Ukraine. In March, however, Russia annexed the peninsula following a hastily called referendum, provoking a major international crisis and sparking instability that has since spread to other parts of Ukraine. Russian President Vladimir Putin is expected to attend Victory Day celebrations in Sevastopol on May 9, which marks both the 69th anniversary of victory over Nazi Germany and the 70th anniversary of the liberation of Sevastopol from German occupation. Pride in the Soviet achievements during World War II has played a major role in Moscow's bid to strengthen its influence in the former Soviet states. -- Robert Coalson