in
a _defile_ it should be thoroughly examined, and sufficient detachments
sent out to cover the main body from attack while effecting the
passage. A neglect of these precautions has sometimes led to the most
terrible disasters.

In military operations very much depends upon the rapidity of marches.
The Roman infantry, in Scipio's campaigns in Africa, frequently marched
a distance of twenty miles in five hours, each soldier carrying from
fifty to eighty pounds of baggage. Septimius Severus, Gibbon states,
marched from Vienna to Rome, a distance of eight hundred miles, in forty
days. Caesar marched from Rome to the Sierra-Morena, in Spain, a distance
of four hundred and fifty leagues, in twenty-three days!

Napoleon excelled all modern generals in the celerity of his movements.
Others have made for a single day as extraordinary marches as the
French, but for general activity during a campaign they have no rivals
in modern history. A few examples of the rapidity of their movements may
not be without interest.

In 1797 a part of Napoleon's army left Verona after having fought the
battle of St. Michaels, on the 13th of January, then marched all night
upon Rivoli, fought in the mountains on the 14th, returned to Mantua on
the 15th, and defeated the army of Provera on the morning of the
16th,--thus, in less than four days, having marched near fifty leagues,
fought three battles, and captured more than twenty thousand prisoners!
Well might he write to the Directory that his soldiers had surpassed the
much vaunted rapidity of Caesar's legions.

In the campaign of 1800, Macdonald, wishing to prevent the escape of
Loudon, in a single day marched forty miles, crossing rivers, and
climbing mountains and glaciers.

In 1805 the grand French army broke up their camp at Boulogne, in the
early part of September, and in two weeks reached their allotted posts
on the Rhine, averaging daily from twenty-five to thirty miles.

During the same campaign the French infantry, pursuing the Archduke
Ferdinand in his retreat from Ulm, marched thirty miles a day in
dreadful weather, and over roads almost impassable for artillery.

Again, in the campaign of 1806, the French infantry pursued the
Prussians at the rate of from twenty-five to thirty miles per day.

In 1808 the advanced posts of Napoleon's army pursued Sir John Moore's
army at the rate of twenty-five miles a day, in the midst of winter.
Napoleon transported an army of fifty thousa