orning, the statement has been made, word reached
General Foch indirectly that air patrols had observed a gap in the
alignment of the German armies between General von Buelow's left and
General von Hausen's right.

During the darkness and the rain, therefore, General Foch had worked two
complete surprises on General von Buelow. He had enveloped the German
commander's right flank, and was safely ensconced there with General
d'Esperey's army behind him, since the latter had by now advanced to
Montmirail. At the same time he had thrust a wedge between Von Buelow and
General von Hausen, threatening General von Buelow's left flank as well.
The first was a seizure of an opportunity, executed with military
promptness, the second was a bold _coup_, and its risk might well have
appalled a less experienced general.

Considering the westernmost of these movements first, it will be seen at
once how the enveloping action brought about the "Affair of the Marshes
of St. Gond." General von Buelow's army was stretched in an arc around
the marshes, which, it will be remembered, have been described as a
pocket of clay, low-lying lands mainly reclaimed, but which become miry
during heavy rains. It was General von Buelow's misfortune, that, on the
very night that his flank was exposed, there should come a torrential
downpour. These same marshes had figured more than once before in
France's military history, and General Foch, as a master strategist, was
determined that they should serve again. When the rain came, he thanked
his lucky stars and acted on the instant.

When the morning of September 9, 1914, dawned, the left wing of General
Foch's army was not only covering the exposed flank of General von
Buelow's forces, but parts of it were two miles to the rear. Under the
driving rain, morning broke slowly, and almost before a sodden and
rain-soaked world could awake to the fact that day had come, General
Foch had nipped the rear of the flank of the opposing army, and was
bending the arc in upon itself. Under normal circumstances, such an
action would tend but to strengthen the army thus attacked, since it
brings all parts of the army into closer communication. But General Foch
knew that the disadvantages of the ground would more than compensate for
this, since the two horns of General von Buelow's army could not combine
without crossing those marshes, now boggy enough, and growing boggier
every second. The task was harder than General Foc