Thirdly, it is a disputed point how far the influence of policy is theoretically allowable during the course of actual operations, _i.e._ after the war has actually begun. Moltke's opinion was that policy should only act at the beginning and at the end of a war, and should keep clear during the actual operations. Clausewitz, however, holds that the two are so intimately related that the political influence cannot be lost sight of even during actual operations. Between two such authorities we may well hesitate to give a definite opinion, and must seek for the middle way. Undoubtedly, in history policy often has really affected the actual operations, as in 1812, 1813, 1814, 1864, Macmahon's march to Sedan, or Bismarck's interference to hurry on the siege of Paris in 1870, or Ladysmith in the Boer War, and in many other cases. That, we must admit. We must also admit that its interference frequently produces a weakening effect on the operations. Clausewitz says that that only occurs when the policy itself is wrong. Perhaps. But the safest middle way rule appears to be this, that policy should be dominant at the beginning and end of a war, but during actual operations the statesman should exercise the greatest possible restraint, and avoid all interference, except when demanded by _overwhelming political necessity_. Fourthly, a politician is bound to study war. He is bound to study war as well as diplomacy, his two instruments. If he only studies how to use one of his two instruments, he will be a poor statesman indeed. It is plain that he MUST study war, so that he may not try to use an instrument of which he knows nothing. It is not meant, of course, that a politician should study all the details of naval and military matters, but only that he should study the general principles of war, and the means, resources, and forces required to attain the political object of war, through the submission of the enemy. Fifthly, in order that the object and the means of policy may harmonize, it is necessary that the one to whom the national interests are entrusted should study the principles of war, so that _he may keep his policy proportionate to the means of enforcing it_. That is to say, he must not propose or commit the nation to a policy which is likely to be strongly opposed by another Power, unless he has from careful study and enquiry made certain that he has sufficient armed force at his disposal, in case the opposing nation suddenly challenges his policy and declares war. He should not even consider a policy without _at the same time_ considering with his military and naval advisers the nation's means of enforcing that policy if challenged to do so. He must not think of embarking upon a war, or of provoking another nation to do so, till he has carefully provided sufficient armed force to give a reasonable prospect, if not a certainty, of success. Otherwise,