ve study and investigation of the Mazurian lakes and swamps.
Again and again he had tramped through them on foot, picked his way
along their treacherous paths on horseback, and finally put their few
roads to the supreme test of the motor car. He knew their every
shortcoming and advantage. His topographical information included
fording places for men and guns, and quicksands.

Much of this knowledge he passed on to younger officers to whom he
lectured at the General Staff College in Berlin, and when, only some
years ago, practically all arrangements had been concluded by powerful
financial interests to drain and cultivate his beloved lakes and swamps
for agricultural purposes, he succeeded in overthrowing these plans at
the last moment. It is said that so powerful were these interests that
Von Hindenburg succeeded only by going, at last, to the emperor himself,
and convincing him that the natural defensive possibilities outweighed
in value any amount of increased acreage of reclaimed land.

We have already shown the problem which faced Von Hindenburg. To drive
the Russians out of East Prussia he had to defeat two armies composed of
at least 500,000 men, whose offensive momentum had been raised to a very
high power by a highly successful advance of more than a week's
duration. He, himself, could count only on far inferior numbers, not
more than the equivalent of four army corps. These he had to assemble
without loss of time and with as much artillery equipment as could be
spared from all directions. From Koenigsberg came the biggest part of the
beaten First Corps and its reserves. What was left of the Twentieth
Corps, of course, was right on the ground. Undoubtedly the fortresses of
Danzig, Graudenz, Thorn, and Posen had to yield parts of their
garrisons. However, most of these were troops of the second line.

On August 23, 1914, Von Hindenburg arrived at Marienburg, about seventy
miles southwest from Koenigsberg and almost as far to the northwest from
Allenstein, and assumed command of the East Prussian forces. Only three
days later, on August 26, 1914, he was ready to put in execution the
plans on which he had worked for almost a lifetime.

[Illustration: Battle of Tannenberg.]

Hindenburg's general strategical plan was as simple as the carrying out
of it, considering the means at his command was difficult. Facing him
were two armies still out of contact with each other, or at least only
very loosely connected. Each