Paul von Hindenburg
Supreme Commander of the Central Powers

In the west, the Germans were hemorrhaging in the battles of Verdun and the Somme. Influential Army officers, led by the artillery expert Lieutenant Colonel Max Bauer, a friend of Ludendorff's, lobbied against Falkenhayn, deploring his futile steamroller at Verdun and his inflexible defense along the Somme, where he packed troops into the front-line to be battered by the hail of shells and sacked commanders who lost their front-line trench. German leaders contrasted Falkenhayn's bludgeon with Hindenburg's deft parrying. The tipping point came when Falkenhayn ordered a spoiling attack by Bulgaria on Entente lines in Macedonia, which failed with heavy losses. Thus emboldened, Romania declared war on Austro-Hungary on 27 August, adding 650,000 trained enemies who invaded Hungarian Transylvania. Falkenhayn had been adamant that Romania would remain neutral. During the Kaiser's deliberations about who should command Falkenhayn said "Well, if the Herr Field Marshall has the desire and the courage to take the post". Hindenburg replied "The desire, no, but the courage—yes". Chancellor Bethmann Hollweg favored Hindenburg, supposing him amenable to moderate peace terms, mistaking his amiability as tractability and unaware that he was intent on enlarging Prussia.

Hindenburg was summoned to Pless on 29 August where he was named Chief of the Great General Staff and, by extension, the Supreme Army Command. Ludendorff demanded joint responsibility for all decisions"; Hindenburg did not demur. Henceforth, Ludendorff was entrusted with signing most orders, directives, and daily press reports. The eastern front was commanded by Leopold of Bavaria, with Hoffmann as his chief of staff. Hindenburg was also appointed the Supreme War Commander of the Central Powers, with nominal control over six million men. Until the end of the war, this arrangement formed the basis of Hindenburg's leadership which would come to be known as the Third OHL.

The British were unimpressed: General Charteris, Haig's intelligence chief, wrote to his wife "poor old Hindenburg is sixty-four years of age, and will not do very much." Conversely, the German War Cabinet was impressed by his swift decision-making. They credited "Old Man Hindenburg" with ending the "Verdun folly" and setting in motion the "brilliant" conquest of Romania.

Hindenburg and Ludendorff visited the Western Front in September, meeting the Army commanders and their staffs as well as their leaders: Crown Prince Rupprecht of Bavaria, Albrecht, Duke of Württemberg and Crown Prince Wilhelm of Prussia. Both crown princes, with Prussian chiefs of staff, commanded Army Groups. Rupprecht and Albrecht were presented with field marshal's batons. Hindenburg told them that they must stand on the defensive until Romania was dealt with, meanwhile defensive tactics must be improved—ideas were welcome. A backup defensive line, which the Entente called the Hindenburg Line, would be constructed immediately. Ludendorff promised more arms. Rupprecht was delighted that two such competent men had "replaced the dilettante 'Falkenhayn'." Bauer was impressed that Hindenburg "saw everything only with the eye of the soldier."
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