Japan's daring plans to conquer Southeast Asia and its rich resources involved several stages. In the complicated fashion typical of the Imperial Navy during World War II, first the American Pacific Fleet would be knocked out of action at Pearl Harbor. Next, the carrier forces that had fought there would cover amphibious invasions in the Dutch East Indies and Malaya. Finally, the First Air Fleet's aircraft carriers would surge into the Indian Ocean to knock out the British Eastern Fleet.

Eastern Fleet, the second game in the Second World War at Sea series, is based on this third stage of Japanese aggression and also covers parts of the second. There are 70 "long" playing pieces, depicting the major fleet units of both sides: battleships, aircraft carriers, cruisers and fleet destroyers. There are also 140 square playing pieces, half the size of the ship pieces, mostly depicting aircraft but also smaller warships and markers.