The Merina royal tradition of taxes paid in the form of labor was continued under the French and used to construct a railway and roads linking key coastal cities to Antananarivo. Malagasy troops fought for France in World War I. In the 1930s, Nazi political thinkers developed the Madagascar Plan that had identified the island as a potential site for the deportation of Europe's Jews. During the Second World War, the island was the site of the Battle of Madagascar between the Vichy French and an Allied expeditionary force.