This article considers the evolution of the French Military Commission in Russia during the First World War. Initially consisting of peacetime structures (the office of the military attaché and his aide), in 1916 the French Military Commission became a strongly centralised and multipurpose military mission whose structure was later borrowed by other Allied nations. The authors use the term 'mission' extensively in the article: its meaning depends on the specific task or duty assigned to a person or group of people and on the extent to which the group was institutionalised. As a result, the term may be understood in two different ways mission as an organisation abroad, including personnel or mission as a business trip, a temporary assignment given to an envoy. In this paper, the term 'mission' is applied to all the forms of the French Military Commission in Russia, whose personnel considerably increased during the war as it shifted into a centralised multifunctional military mission. The need to establish effective interaction among the members of the Entente and the growing number of issues the French military attaché in Russia had to deal with conditioned the transformation of French military representation. The project was initiated by Commander-in-Chief Joseph Joffre. Joffre based his decisions on the reports of Major Langlois, who visited Russia eight times between February 1915 and February 1917. Joffre managed to turn the small and rather ineffective mission, distrusted by Russian generals, into a centralised military mission. General Maurice Janin was appointed head of the new commission, and it was under his leadership that it became the centre of coordination for French military activities in Russia.