It may not be uninteresting to trace the probable effects which these movements would have produced.
General Junot had taken the command of the whole disposable force under his orders in Portugal (amounting to 14,000 men), at Torres Vedras on the 20th; and presuming upon the boasted superiority of French troops to those of any other nation, he had resolved to attack the left of the British army, thereby leaving it no retreat if defeated, but to the sea-shore, and to its transports, if it could effect its embarkation. With this intention he marched on the night of the 20th by a road leading through a most difficult defile, which brought him to the eastward of Vimiera, near which place he arrived soon after nine o’clock on the 21st. The order which had been issued the day before for the British army was to march at five o’clock, by the road to the Ponte de Roll, and from thence direct upon Mafra. This road was separated about two leagues from that upon which the French army was advancing, and leading in a totally different direction; divided also from it by a woody and almost impervious tract of country; so that if the movement had been executed, the British army would have been considerably advanced towards Mafra, before the enemy had arrived at Vimiera.
If indeed this march had been discovered by the French patroles, it would still have been impossible to arrest our progress, from the difficulty of getting to us; and in all probability, the enemy would have had no other resource than to have returned to Torres Vedras (where the whole of his baggage had remained), and from thence tried to attack us at Mafra, which would have been attempted under many disadvantages; or to have marched in the greatest haste by the Cabeça de Montachique to have covered Lisbon. To those who are acquainted with the country I am speaking of, the difficulty of such movements (with an army which had already been marching since the morning of the 20th), will be duly appreciated: if the attempt to cover the capital had been made, the confusion and hurry with which a position must have been taken up would have bid fair for the success of our attack upon it, which could not have been delayed beyond the 23d; the proximity of Lisbon, which was ripe for insurrection, must have added to the difficulties of the enemy; and upon a review of all the circumstances of the case, together with the great talents which Sir Arthur Wellesley has since displayed, we may be warranted in believing that complete success would have attended his operation; and that the possession of Lisbon would have been effected with a smaller loss, with greater advantages, and at a much earlier period, than it was obtained by the system which was adopted.