On 26, August 1914 German 17th corps, 1st reserve corps and 6th mixed territorial brigade defeated Russian 6th corps in the north of Bischofsburg. Japanese general staff drew figures on the map which German officers actually used. Red lines show the directions Germans took. Blue lines are for dispositions of Russians in the early morning. 4th division of Russian 6th corps went far north. they encountered three and a half times stronger enemy. This was because of Russian failure of scouting.

Straight line from top right to bottom left is a railway from Koenigsberg to Allenstein which still exists today in Poland and Russian Federation.

During World War One Japanese military observers interviewed with Russian Officers in Jilinsky's headquarters. They tried to clarify how Russians viewed German deployment in Tannenberg. Russians replied that they estimated one corps in Koenigsberg seemed to be 1st corps. In the south of Allenstein there was a corps seemed to be 20th corps. Next to 20th in a row there were 17th corps, 19th corps and part of 1st reserve corps. The rest of Germans retreated to River Vistula.

Russians misunderstood actual 1st corps as 17th corps and 1st reserve corps. As a result actual 17th corps and 1st reserve corps were in the air. They thought German would use railways for transportation and so would not walk. It was a fatal mistake to them.

Both 17th corps and 1st reserve corps marched 30km a day on foot. However, they delayed half a day from the expectation of 8th army's headquarters. That was because refugees and livestock occupied all of main roads from east to west.

The soldiers took bypaths covered by sand. It was not easy for Russian reconnaissance air crafts to sight walking German soldiers. Most of their information was acquired by spies living in big cities.