Modern history:

Four years into the 20th century saw the Russo-Japanese War with the Battle of Port Arthur establishing the Empire of Japan as a world power. The Russians were in constant pursuit of a warm water port on the Pacific Ocean, for their navy as well as for maritime trade. The Manchurian Campaign of the Russian Empire was fought against the Japanese over Manchuria and Korea. The major theatres of operations were Southern Manchuria, specifically the area around the Liaodong Peninsula and Mukden, and the seas around Korea, Japan, and the Yellow Sea. The resulting campaigns, in which the fledgling Japanese military consistently attained victory over the Russian forces arrayed against them, were unexpected by world observers. These victories, as time transpired, would dramatically transform the distribution of power in East Asia, resulting in a reassessment of Japan's recent entry onto the world stage. The embarrassing string of defeats increased Russian popular dissatisfaction with the inefficient and corrupt Tsarist government.

Please answer a question about this article. If the question is unanswerable, say "unanswerable". Why did the Manchurian Campaign fight the Russians.
over Manchuria and Korea.