up with the Russian First Army, commanded by General Paul von Rennenkampf, which had started advancing into the north-east section of East Prussia. However, lack of communications between the two armies, and with the rear command of the Northwest Army Group, hindered co-ordination. It is sometimes claimed that the poor coordination between Samsonov and Rennenkampf during the campaign was based on their personal antagonism towards each other. This antagonism is said to have been based on an incident after the Battle of Liaoyang during the Russo-Japanese War where Samsonov had publicly quarrelled with Rennenkampf on the landing platform of a railway station, and that the two were mutual lifetime enemies. However, the original source of this story is considered to be Max Hoffmann, at that time a colonel on the staff of the German Eighth Army. His claim of first hand knowledge of the disagreement is contradicted by the injuries to Rennenkampff at the time. Hoffman appears to have advanced this story during planning sessions, in support of his argument that Rennenkampf would not come to the aid of Samsonov. He argued that the German Eighth Army was free to use all of its forces in the attack on the Russian Second Army to their south, without fear of a counter-attack from their rear by the Russian First Army. Battle of Tannenberg Rennenkampf and the Russian First Army were the first to encounter the German Eighth Army, winning the Battle of Gumbinnen. The defeat led the German High Command to dismiss von Prittwitz and his chief of staff, replacing them with General (later Field Marshal) Paul von Hindenburg and General Erich Ludendorff. Hindenburg and Ludendorff arrived on the Eastern Front and decided to attack Samsonov's advancing forces with the full weight of the Eighth Army. Hindenburg and Ludendorff were strengthened in making this decision by intercepted Russian wireless communications, which indicated that Rennenkampf and the Russian First Army could not reach the proposed battle in time to be of assistance, and by an intercepted order from Samsonov, showing the movement of his forces. The armies made contact on August 22 and for six days the numerically superior Russians had some success. However, by August 29 the Germans had surrounded Samsonov's Second Army in the woods between Allenstein and Willenberg. The rout that followed was named the Battle of Tannenberg by Hindenburg, to compensate for a defeat of the Teutonic Knights