The Siege and Battle of Port Arthur marked the commencement of the Russo-Japanese War. Porth Artur was the deep-water port and Russian naval base at the tip of the Liaodong Peninsula in Manchuria. Port Arthur was widely regarded as one of the most strongly fortified positions in the world at the time. It was the longest and most violent land battle of the Russo-Japanese War. Russian land forces in the course of the siege suffered 31,000 casualties, of whom 15,000 were killed, wounded, and missing.