In August 1937, Leipziger completed a utopian science fiction novel, mostly in German, entitled La Grande Compagnie de Colonisation: Dokumente eines Grossen Planes.
Written in the form of a collection of fictional meeting minutes, press releases, private letters, telegrams and newspaper clippings, the book tells the story of a corporation based in Luxembourg, chartered with the purpose of developing all unused and unpopulated regions in the world.
The company eventually succeeds in its goal, overcoming various forms of nationalist opposition to accomplish massive works: irrigating deserts, closing the Straits of Gibraltar and the Bosporus, building a canal through Nicaragua, tunneling under the English Channel, developing the mineral resources of South America and creating arable land in China.
Over the decades following World War II, Leir built upon these personal, bi-national relationships to attract several major American corporations to Luxembourg, among them Goodyear, DuPont, Monsanto Company, Wells Fargo and Bank of America.
In 1963 Armand Hammer's Occidental Petroleum acquired Leir's company Interore SA, a phosphate mining and chemical trading multinational with operations in twenty-seven countries.
The edition also included a postscript by Christian Calmes (1913–95), a former Secretary General of the Council of Ministers of the European Communities in Brussels and grand marshal of the royal court of Luxembourg.