Napoleon was, at the same time, pouring in constant reinforcements over the Pyrenees, and strengthening his _corps d’armée_ in every province on the Peninsula. The corps of Ney, Junot, and Reynier, having united at Salamanca, comprised seventy thousand men, of which six thousand were cavalry; and Massena arrived from France, by the express command of Napoleon, to assume the command-in-chief. A part of the imperial guard crossed the Pyrenees to reinforce the army of the centre; and another body received orders to hold itself in readiness to march, and as it was generally believed, to form a body-guard for the Emperor. But still, notwithstanding the gloomy prospects of the British, it was surprising what a number of desertions took place from the enemy’s corps. Between the commencement of 1810 and the month of May, nearly five hundred men, chiefly Germans and Italians, arrived, time after time, at the British outposts; while desertions from the English regiments were extremely rare. Early in May, Massena prepared for active operations, and invested the fortress of Rodrigo--the inferiority of Lord Wellington’s force rendering any attempt on his part to prevent it impossible. All that could be done was to observe the enemy closely; and for this purpose, head-quarters were transferred to Almeida--which, after a few days, were farther retired to Alverca, six leagues in the rear. The investment of Rodrigo, which occasional advances of the British had partially relaxed, became now more serious--for Ney determined that the place should fall--and taking post on a range of high grounds with thirty thousand men, he covered effectually the operations carried on by Junot, whose separate force amounted to forty thousand more. It was now ascertained that Matagorda[100] had fallen,--that Cadiz, of course, must yield,--that divisions of the guards had entered Madrid,--and that Napoleon was absolutely across the Pyrenees. Other tidings were of better import. Ballasteros was on the Guadalquiver, and so threatening in his movements, as to require Reynier to be detached to check him; while the mountain districts were swarming with guerillas, who cut off every detached party of the French, plundered their convoys, interrupted their communications, and kept the whole of their posts constantly on the alert. In Castile particularly, their audacity was boundless. They had carried off an aide-de-camp of Kellerman from the gates of Valladolid; and no Frenchman could trust himself in the open country without a powerful escort.