Soult destroyed his artillery and baggage, and hastily retreated through the mountain passes; but his army was again arrested at the river Cavado, and placed on the very brink of destruction, when the brave and skilful Dulong succeeded in effecting a passage at the Ponte Nova; the same daring officer opened, on the same day, a way for the further escape of the French across the Misarella by the Saltador.
In the pursuit of Massena, in 1810, it was important to the English to cross the Guadiana, and attack the French before Badajos could be put in a state of defence.

Beresford was directed by Wellington to pass this river at Jerumina, where the Portuguese had promised to furnish pontons; but they neglected to fulfil their engagement, and the army had to wait till Capt.

Squire, an able and efficient officer of engineers, could construct other means for effecting a passage.

Every thing was done that genius could devise and industry execute; nevertheless, the operations of the army were greatly delayed--"_a delay,_" says the historian, "_that may be considered as the principal cause of those long and bloody operations which afterwards detained Lord Wellington more than a year on the frontiers of Portugal._" We might prolong these remarks by discussing the passages of the Ceira and Alva, and their influence on the pursuit of Massena; Wellington's passage of the Tagus, and his retreat from Burgos in 1812; the passage of the Adour and Garonne in 1814; and the failure of the mines to blow up the bridges of Saltador, Alcantara, &c.; but a sufficient number of examples, it is believed, has already been adduced to show the advantage of maintaining a properly organized and instructed body of sappers, miners, and pontoniers, and the fatal results attending the want of such troops, as a component part of an army organization.
It has already been remarked that the infantry of an army must always form the basis of the apportionment; and by the general rule laid down by military writers, the cavalry should be from one-fourth to one-sixth of the infantry, according to the character of the war; the artillery about two-thirds of the cavalry, or one-seventh of the infantry; and the engineers from one-half to three-fourths of the artillery,--say about two-thirds.

The staff and administrative corps must vary according to the nature of the organization, and the character of the theatre of war.
The former ought to be from two to five in a thousand, and the latter from twenty-five to seventy-five,[40] as a general rule.