The traditions of the United States, of course, forbade their intervention in the Franco-Prussian dispute. By an article of their political creed termed the Monroe Doctrine, they asserted their resolve not to interfere in European affairs and to prevent the interference of any strictly European State in those of the New World. It was on this rather vague doctrine that they cried "hands off" from Mexico to the French Emperor; and the abandonment of his _protégé_, the so-called Emperor Maximilian, by French troops, brought about the death of that unhappy prince and a sensible decline in the prestige of his patron (June 1867). Russia likewise remembered Napoleon III.'s championship of the Poles in 1863, which, however Platonic in its nature, caused the Czar some embarrassment. Moreover, King William of Prussia had soothed the Czar's feelings, ruffled by the dethroning of three German dynasties in 1866, by a skilful reply which alluded to his (King William's) desire to be of service to Russian interests elsewhere--a hint which the diplomatists of St. Petersburg remembered in 1870 to some effect. For the rest, the Czar Alexander II. (1855-81) and his Ministers were still absorbed in the internal policy of reform, which in the sixties freed the serfs and gave Russia new judicial and local institutions, doomed to be swept away in the reaction following the murder of that enlightened ruler. The Russian Government therefore pledged itself to neutrality, but in a sense favourable to Prussia. The Czar ascribed the Crimean War to the ambition of Napoleon III., and remembered the friendship of Prussia at that time, as also in the Polish Revolt of 1863[11]. Bismarck's policy now brought its reward. [11] See Sir H. Rumbold's _Recollections of a Diplomatist_ (First Series), vol. ii. p. 292, for the Czar's hostility to France in 1870. The neutrality of Russia is always a matter of the utmost moment for the Central Powers in any war on their western frontiers. Their efforts against Revolutionary France in 1792-94 failed chiefly because of the ambiguous attitude of the Czarina Catherine II.; and the collapse of Frederick William IV.'s policy in 1848-51 was due to the hostility of his eastern neighbour. In fact, the removal of anxiety about her open frontier on the east was now worth a quarter of a million of men to Prussia.