When WWI broke out, Hindenburg was retired in Hanover. On 22 August, he was selected by the War Cabinet and the German high command ("Oberste Heeresleitung", OHL) to assume command of the German Eighth Army in East Prussia, with General Erich Ludendorff as his chief of staff. After the Eighth Army had been defeated by the Russian 1st Army at Gumbinnen, it had found itself in danger of encirclement as the Russian 2nd Army under General Alexander Samsonov advanced from the south towards the Vistula River. Momentarily panicked, Eighth Army commander Maximilian von Prittwitz notified OHL of his intent to withdraw his forces into Western Prussia. The Chief of the German General Staff, "Generaloberst" Helmuth von Moltke, responded by relieving Prittwitz and replacing him with Hindenburg.