and the character and position of the enemy. In case of an attack they
retire slowly, and on joining the main body, take their assigned
position in the line of battle.

In an open country the order of march presents but little difficulty;
but in a broken country, and especially in the vicinity of the enemy, a
march cannot be conducted with too many precautions. Before engaging 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. Cæsar 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