The morning the Treaty of Versailles is signed, Germany's High Seas Fleet, the world's second-largest navy, sits scuttled at the bottom of Scapa Flow, sunk by its own crews rather than handed over to Britain. This episode picks up the naval arms race that follows: Britain, the United States, and Japan racing to build ever larger battleships until Charles Evans Hughes, the US Secretary of State, convenes the Washington Conference to force limits on tonnage and firepower. The resulting treaty scraps dozens of ships and puts America on equal footing with Britain, but demotes Japan to a smaller fleet than either power, breeding resentment that pushes Japanese planners toward secret construction. By the mid-1930s Italy, the Soviet Union, and a rearming Germany are expanding their battle fleets again, with Hitler's regime openly defying Versailles to build compact, heavily armed 'pocket battleships.' The episode closes on September 1, 1939, as the naval buildup it has traced ends in the opening shots of the Second World War.