Had he waited but a few days before pressing Wellington hard, he would have been reinforced by King Joseph with 14,000 men.[307] But he preferred to risk all on a last dashing move rather than to wait for the King and contribute, as second in command, to securing a substantial success.
The correspondence of Joseph before and after Salamanca is instructive.

We see him unable to move quickly to the support of Marmont, because the French Army of the North neglects to send him the detachment needed for the defence of Madrid; and when, on hearing the news of Salamanca, he orders Soult to evacuate Andalusia so as to concentrate forces for the recovery of the capital, his command is for some time disobeyed.

When, at last, Joseph, Soult, and Suchet concentrate their forces for a march on Madrid, Wellington is compelled to retire.

Pushing on his rear with superior forces, Joseph then seeks to press on a battle; but again Soult moves so slowly that Wellington is able to draw off his men and make good his retreat to Ciudad Rodrigo.[308] Apparently Joseph came off victor from the campaign of 1812; but the withdrawal of French troops towards Madrid and the valley of the Douro had fatal consequences.

The south was at once lost to the French; and the sturdy mountaineers of Biscay, Navarre, and Arragon formed large bands whose persistent daring showed that the north was far from conquered.