ght in the
best school of the military art.

Frederick III. of Denmark had declared war without making preparations
for it, fancying that Charles would be forced to remain with his army in
Poland and that he would have abundant time to act. He quickly learned
his mistake. With an army of eight thousand well-trained veterans Charles
marched at all speed from Poland, and a few months after war was declared
stood with his compact little army on Denmark's shores.

Taken by surprise, the Danish general, Bilbe, retreated hastily northward
and the whole peninsula of Jutland was quickly overrun by the Swedes.
Bilbe had much the larger army, but they were mainly raw recruits, and he
dared not face the veterans of the Thirty Years' War. The Danes had
projected an invasion of Sweden, for which they had been deliberately
preparing, and were overwhelmed to find their army in retreat and a force
of six thousand men closely besieged in the Fredericia fortress. A night
attack by General Vrangel won this stronghold for the Swedes, with its
garrison and a large amount of arms and provisions.

So far the movement of Charles had been brilliantly successful, but his
position was very dangerous. Enemies were advancing on him from various
sides, a Polish army having invaded Pomerania, an Austrian army having
advanced into Prussia, while the elector of Brandenburg had joined his
enemies. His ally, England, had promised to aid him with a fleet, but it
failed to appear, and the situation was growing daily more critical. From
his awkward position he was rescued by a combination of daring and the
favoring influences of nature.

The winter of 1658 proved extraordinarily cold. Never within the memory
of man had such bitter weather been known. The sea that flowed between
the Danish islands was tightly frozen, a natural bridge of ice connecting
them with one another and the mainland. With bold resolution King Charles
determined to cross to the island of Fyen.

The enterprise was full of risk. The ice swayed perilously beneath the
marching hosts. At places it broke. But the island shore was safely
reached, the troops guarding it were beaten, and soon the whole island
was in Charles's possession.

But a more daring and perilous enterprise confronted the king. There was
a broader arm of the sea to cross, the Great Belt, about twelve miles
wide. The ice was examined and tested by the quartermaster-general, who
said that he would answer with his life