When the Kingdom of Romania entered the Great War in 1916, it was supposed to receive aid from the Entente allies While the Russian troops fought alongside the Romanians on the Eastern Front, the Western allies assisted them with arms, financial resources, and experienced officers. Military cooperation in the various European theatres of war was a rather complex task, and its arrangement actualised the issues of cooperation between the allies in arms in pursuit of a common goal. The French Mission of General Berthelot assisted the Romanian army in a number of ways, including leading the fighting in the autumn of 1916, reorganising the defeated Romanian army, and acting as military advisers in the 1917 campaign. In that respect, the French were competing with the Russians for influence over the Romanian top leadership, especially the military command. The formation of the Romanian front, consisting mainly of Russian troops, allowed the Russian Stavka to sideline the French from directly influencing the course of military operations. The work of the French mission was limited to bringing the Romanian units withdrawn to the rear back into order. However, in 1917, the French resumed their leading role in influencing the Romanian generals. The February Revolution marked a turning point in relations between the rival partners, finally consolidating the leading role of the Berthelot Mission in the affairs of the Romanian Army on the Romanian front. The French Mission helped reorganise the Romanian Army, which played a decisive role in the final stage of the Great War. This allowed the Kingdom of Romania to remain among the victorious nations, despite the vicissitudes of 1918 following the withdrawal of Russia from the war. The main sources for this article are documents from the Russian State Military Historical Archive (RGVIA) relating primarily to the competence of the central military authorities and administration during the war period, namely the Supreme Command Headquarters and the General Staff Headquarters.