Gaius and Charlemagne and President Truman seem to be working hand in hand across the centuries to bring about coördination of European inland waterways. Under the law of the Roman Empire such waterways, when constituting or crossing international boundaries, were free to use by all nations within the Empire. Since 1815, as we shall presently see, there have been successive organized attempts, mostly unsuccessful, to revive and apply this principle of freedom of navigation of the Roman Law on the Rhine, the Danube, and elsewhere. The United States, through President Truman, at the July–August Berlin (Potsdam) conference of the victorious allies, proposed that navigation over the internal waterways of Continental Europe be free to all nations under international control. More recently, in the latter weeks of 1945, grave obstacles and problems threaten the realization of the Truman proposal. The writer believes that if we visualize clearly the mechanism and workings of an international body vested with control of inland river navigation, we can better appraise the merits of that proposal.