In 1914, on this day the German Deputy Chief of Operations, Colonel Max Hoffmann received a new radio intercept of von Rennenkampf's most recent order for the Russian First Army to relieve General Samsonov's beleagured Second Army at Tannenberg.
Marching through East PrussiaThat the Russian Commanders would BOTH send messages in clear text was so unbelievable that his incredulous bosses refused to accept it as a statement of fact. Instead Ludendorff and Hindenburg compounded this error by rejecting Hoffman's plans, and then insisting that German I Corps under Hermann von François press ahead with the attack even before his artillery supplies arrived.
Of course von Rennenkampf and Samsonov had hated each other even before their notorious punch up on the platform of Mukden Station in 1905. But to Hoffman's private exasperation it was Ludendorff and Hindenburg who quarreled over tactics having only just met on the train en route. Ironically, Hindenburg's reactivation from retirement was a desperate measure forced upon the High Command by the panicking aristocracy of East Prussia. And worse, Hoffman's defensive plans were perfectly sound and the interference of the two Generals was not only wholly unnecessary but in fact totally counter-productive.
Fortunately for the Central Powers, the German Army Chief of Staff Helmuth von Moltke had exercised caution by taking three corps and a cavalry division from the Western front and redeploying them to East Prussia. This order was issued over the head of Ludendorff who had protested that the relief forces would arrive too late to have any effect, while at the same time weakening the German offensive through Belgium against France. Although he was right to argue that this massive redeployment threatened to undo the Schlieffen Plan, the early arrival of these Corps was now key to saving the Eastern Front from collapse.