[6] Frederick van Millingen maintained poor relations with the rest of his family, and soon joined the Ottoman Army after converting to Islam and taking on the name of Osman Bey.
In it, he criticized supposed Jewish plots for world domination centered around the Alliance Israélite Universelle, and considered the Jews to be responsible, directly or indirectly, for events such as the French Revolution.
In 1886, while in Russian service, he wrote an essay, called by Walter Ze'ev Laqueur "one of the most remarkable books ever written outside a lunatic asylum",[8] outlining several conspiracy theories regarding the assassination of Tsar Alexander II of Russia.
Thus, alongside Lutostansky and Hermann Goedsche, Millingen was one of the first European writers to popularize the idea of an "international Jewish conspiracy" in Europe.
In French: In English: In Italian: In German: Frederick van Millingen appears as a minor character in Umberto Eco's novel The Cemetery of Prague.