Curious Notions

Curious Notions is an alternate history novel by Harry Turtledove. It is a part of the Crosstime Traffic series. In Curious Notions, the Central Powers won World War I prior to the United States entering the war. Subsequently, the German Empire invaded and conquered the United States in the 1950s. The story is set 150 years later, in German-occupied San Francisco. The main plot deals with time travelers from our universe establishing an electronics shop in San Francisco, coming under the suspicion of both the German authorities and the Tongs while preventing the Germans from duplicating the time travel technology.

The Central Powers win by managing to knock out France and the British Expeditionary Force in the west towards the beginning of the war. Then they defeat Russia before the United States can intervene. A few years later, the German Empire intervenes in the Russian Revolution and defeats the Bolsheviks, but the Russian Empire is mostly divided and therefore no longer a power. Britain and France tried to stop Germany's power again in the late 1930s, but since the United States does not intervene, they lose and Germany gains control over Europe and its sphere of influence. Germany is also able to restore the monarchies of Brazil, China and Portugal.