Well, the Russian and Ottoman Empires have always been at odds over the black sea, and even today, Russia and Turkey are still at odds over it. Also, Russia and Britain were at odds over control over Central Asia, in what is called the Great Game. This centered in Afghanistan, because he who controls Afghanistan controls the continent. In 1856 Russia occupied what makes up modern-day Romania in an effoert to control the Black Sea. Why do the Russians want the Black Sea? Well, they have always wanted an open warm-water port, the closest they ever came to one was during the Russo-Japanese War. So when war broke out when the Russians refused to withdrawl from the Ottoman Empire, Britain enetered the war on their side. Also, France, having an alliance with the Ottoman Empire, declared war on Russia. Sardinia, having an alliance with France, declared war on the Russians as well.
