nearly seventy, whose military career had made so slight an impression
on the German mind that his name was not even included in the German
"Who's Who." Nevertheless he had commanded corps on the Prussian
frontier, and even after his retirement made the study of its defence
his hobby. He knew every yard of the intricate mixture of land and
water which made up the district of the Masurian Lakes, and had,
unfortunately for Russia, defeated a German financial scheme for
draining the country and turning it into land over which an invader
could safely march. Within five days of Samsonov's victory,
Hindenburg, taking advantage of the magnificent system of German
strategic railways, had collected some 150,000 men from the fortresses
on the Vistula and concentrated them on a strong position stretching
from near Allenstein south-west towards Soldau, his left resting on
the railway from Eylau to Insterburg and his right on that from Eylau
to Warsaw. In front of him were marshes with the ways through which he
was, but Samsonov was not, familiar; and the railways enabled him to
threaten either of the enemy's flanks.

Samsonov was practically isolated. Rightly ignoring the strong
defences of Königsberg but wrongly getting out of touch with
Rennenkampf, he had pushed on, thinking there could be no serious
resistance east of the Vistula and hoping to seize the bridge at
Graudenz. Hindenburg made a feint on his right, but pushed his real
outflanking movement along the railway on his left. But the feint was
enough to outflank Samsonov's left and close the retreat towards
Warsaw. It also diverted his reserves from his centre and from his
right, which on the 27th was cut off from a possible junction with
Rennenkampf. A gallant attempt by Gourko to relieve him on the 30th
came too late. The only exit was along a narrow strip of land between
the marshes leading to Ortelsburg, and here between the 28th and the