World War I marked the final point of the continuous process of fiduciarisation of money, of the detachment from its substance, the final point of establishing « Russian type of ideal money ». Paper currency was a Russian tradition, since 1769, until the introduction of the gold standard in 1897. The war brought back the dominance of the paper currency. In this paper, I will consecutively dwell on: (i) the role of paper currency and loans during the war and the discussions among the leading Russian economists as regards the evolution of the monetary regime. I will then examine, (ii) Tugan’s business cycle (conjunctural) theory of the value of money associated with aggregate demand, and especially with the development of the model of money demand and its endogeneity, and finally (iii) on Tugan’s proposals for managed paper currency by controlling the exchange rate.