Authored by an international team of researchers, this article considers the evolution of political and diplomatic relations between Russia and France, with a special emphasis on the events of 1555, when France attempted to create a European alliance to fight the emperor of the Holy Roman Empire. The authors analyse a letter from Henry II de Valois, king of France, to Ivan IV, tsar of Russia. The letter was accompanied by messages from the king to the Turkish sultan, the Swedish king and the French ambassador at Constantinople, explaining the mission of Hans Schlitte, a Saxon merchant authorised by the Moscow royal court to negotiate in Europe. The article is accompanied by all four documents, which have never been introduced to historians previously.