Obviously, the weak point of plans so elaborate is that they cannot readily be changed. Neither even can they, save with difficulty, be modified. Even in face, therefore, of a declaration of war by Great Britain, the plan had to be adhered to. Unless it could be adhered to, the invasion of France must be given up. Bearing in mind the labour and cost of preparation, the hopes built upon the success of the invasion, and the firm belief that the opposition to be expected by Belgium could at most be but trifling, it ceases to be surprising that, though there was every desire to put off that complication, a war with Great Britain proved no deterrent. Further, the construction by the French just within their Eastern frontier of a chain of fortifications extremely difficult to force by means of a frontal attack, and quite impossible to break if defended by efficient field forces, manifestly suggested the plea of adopting the shorter and more advantageous route on the ground of necessity. In dealing with that plea it should not be forgotten that the State which elects to take the offensive in war needs resources superior to those of the State which elects to stand, to begin with, upon a policy of defence. Those superior resources, save in total population, Germany, as compared with France, did not possess. In adopting the offensive, therefore, on account of its initial military advantages, Germany was risking in this attack means needed for a prolonged struggle. It was necessary in consequence for the attack to be so designed that it could not only not fail, but should succeed rapidly enough to enable the attacking State to recoup itself--and, possibly, with a profit. The conditions of first rapidity, and second certainty, formed the _political_ aspects of the plan, and they affected its military aspects in regard to first numbers, secondly equipment, thirdly route. But there were, if success was to be assured, still other conditions to be fulfilled, and these conditions were _purely_ military. They were:-- (1) That in advancing the line of the invading armies must not expose a flank, and by so doing risk delay through local or partial defeat. (2) That the invading armies must not lay bare their communications. Risk to their communications would also involve delay. (3) That they must at no point incur the hazard of attacking a defended position save in superior force. To do so would again risk repulse and delay. Did the plan drawn up by the German General Staff fulfil apparently all the conditions, both political and military, and did it promise swift success? It did.