Editing Schlieffen Plan (section)

===1940s – 1990s===
====Gerhard Ritter====
In ''Sword and the Sceptre; The Problem of Militarism in Germany'' (1969), [[Gerhard Ritter]] wrote that Moltke the Elder changed his thinking to accommodate the change in warfare evident since 1871, by fighting the next war on the defensive in general,

{{quote|All that was left to Germany was the strategic defensive, a defensive, however, that would resemble that of Frederick the Great in the Seven Years' War. It would have to be coupled with a tactical offensive of the greatest possible impact until the enemy was paralysed and exhausted to the point where diplomacy would have a chance to bring about a satisfactory settlement.{{sfn|Foley|2007|p=24}}}}

Moltke tried to resolve the strategic conundrum of a need for quick victory and pessimism about a German victory in a {{lang|de|Volkskrieg}} by resorting to {{lang|de|Ermattungsstrategie}}, beginning with an offensive intended to weaken the opponent, eventually to bring an exhausted enemy to diplomacy, to end the war on terms with some advantage for Germany, rather than to achieve a decisive victory by an offensive strategy.{{sfn|Foley|2007|pp=23–24}} In ''The Schlieffen Plan'' (1956, trans. 1958), Ritter published the Schlieffen Memorandum and described the six drafts that were necessary before Schlieffen was satisfied with it, demonstrating his difficulty of finding a way to win the anticipated war on two fronts and that until late in the process, Schlieffen had doubts about how to deploy the armies. The enveloping move of the armies was a means to an end, the destruction of the French armies and that the plan should be seen in the context of the military realities of the time.{{sfn|Foley|2007|pp=69, 72}}

====Martin van Creveld====
In 1980, [[Martin van Creveld]] concluded that a study of the practical aspects of the Schlieffen Plan was difficult, because of a lack of information. The consumption of food and ammunition at times and places are unknown, as are the quantity and loading of trains moving through Belgium, the state of repair of railway stations and data about the supplies which reached the front-line troops. Creveld thought that Schlieffen had paid little attention to supply matters, understanding the difficulties but trusting to luck, rather than concluding that such an operation was impractical. Schlieffen was able to predict the railway demolitions carried out in Belgium, naming some of the ones that caused the worst delays in 1914. The assumption made by Schlieffen that the armies could live off the land was vindicated. Under Moltke the Younger much was done to remedy the supply deficiencies in German war planning, studies being written and training being conducted in the unfashionable "technics" of warfare. Moltke introduced motorised transport companies, which were invaluable in the 1914 campaign; in supply matters, the changes made by Moltke to the concepts established by Schlieffen were for the better.{{sfn|Creveld|1980|pp=138–139}}

Creveld wrote that the German invasion in 1914 succeeded beyond the inherent difficulties of an invasion attempt from the north; peacetime assumptions about the distance infantry armies could march were confounded. The land was fertile, there was much food to be harvested and though the destruction of railways was worse than expected, this was far less marked in the areas of the 1st and 2nd armies. Although the amount of supplies carried forward by rail cannot be quantified, enough got to the front line to feed the armies. Even when three armies had to share one line, the six trains a day each needed to meet their minimum requirements arrived. The most difficult problem was to advance railheads quickly enough to stay close enough to the armies. By the time of the Battle of the Marne, all but one German army had advanced too far from its railheads. Had the battle been won, only in the 1st Army area could the railways have been swiftly repaired; the armies further east could not have been supplied.{{sfn|Creveld|1980|p=139}}

German army transport was reorganised in 1908 but in 1914, the transport units operating in the areas behind the front line supply columns failed, having been disorganised from the start by Moltke crowding more than one corps per road, a problem that was never remedied but Creveld wrote that even so, the speed of the marching infantry would still have outstripped horse-drawn supply vehicles, if there had been more road-space; only motor transport units kept the advance going. Creveld concluded that despite shortages and "hungry days", the supply failures did not cause the German defeat on the Marne, Food was requisitioned, horses worked to death and sufficient ammunition was brought forward in sufficient quantities so that no unit lost an engagement through lack of supplies. Creveld also wrote that had the French been defeated on the Marne, the lagging behind of railheads, lack of fodder and sheer exhaustion, would have prevented much of a pursuit. Schlieffen had behaved "like an ostrich" on supply matters which were obvious problems and although Moltke remedied many deficiencies of the {{lang|de|[[Etappendienst]]}} (the German army supply system), only improvisation got the Germans as far as the Marne; Creveld wrote that it was a considerable achievement in itself.{{sfn|Creveld|1980|pp=139–140}}

====John Keegan====

In 1998, [[John Keegan]] wrote that Schlieffen had desired to repeat the frontier victories of the Franco-Prussian War in the interior of France but that fortress-building since that war had made France harder to attack; a diversion through Belgium remained feasible but this "lengthened and narrowed the front of advance". A corps took up {{cvt|29|km|order=flip}} of road and {{cvt|32|km|order=flip}} was the limit of a day's march; the end of a column would still be near the beginning of the march, when the head of the column arrived at the destination. More roads meant smaller columns but parallel roads were only about {{cvt|1|–|2|km|order=flip}} apart and with thirty corps advancing on a {{cvt|300|km|order=flip}} front, each corps would have about {{cvt|10|km|order=flip}} width, which might contain seven roads. This number of roads was not enough for the ends of marching columns to reach the heads by the end of the day; this physical limit meant that it would be pointless to add troops to the right wing.{{sfn|Keegan|1998|pp=36–37}}

Schlieffen was realistic and the plan reflected mathematical and geographical reality; expecting the French to refrain from advancing from the frontier and the German armies to fight great battles in the [[hinterland]] was found to be [[wishful thinking]]. Schlieffen pored over maps of Flanders and northern France, to find a route by which the right wing of the German armies could move swiftly enough to arrive within six weeks, after which the Russians would have overrun the small force guarding the eastern approaches of Berlin.{{sfn|Keegan|1998|pp=36–37}} Schlieffen wrote that commanders must hurry on their men, allowing nothing to stop the advance and not detach forces to guard by-passed fortresses or the lines of communication, yet they were to guard railways, occupy cities and prepare for contingencies, like British involvement or French counter-attacks. If the French retreated into the "great fortress" into which France had been made, back to the Oise, Aisne, Marne or Seine, the war could be endless.{{sfn|Keegan|1998|pp=38–39}}

Schlieffen also advocated an army (to advance with or behind the right wing), bigger by {{nowrap|25 per cent,}} using untrained and over-age reservists. The extra corps would move by rail to the right wing but this was limited by railway capacity and rail transport would only go as far the German frontiers with France and Belgium, after which the troops would have to advance on foot. The extra corps ''appeared'' at Paris, having moved further and faster than the existing corps, along roads already full of troops. Keegan wrote that this resembled a plan falling apart, having run into a logical dead end. Railways would bring the armies to the right flank, the Franco-Belgian road network would be sufficient for them to reach Paris in the sixth week but in too few numbers to defeat decisively the French. Another {{nowrap|200,000 men}} would be necessary for which there was no room; Schlieffen's plan for a quick victory was fundamentally flawed.{{sfn|Keegan|1998|pp=38–39}}