[2] In August 1808 he joined a Cavalry unit formed in Ciudad Rodrigo, and led a small band of lancers that skirmished with the French forces in the south of the region of Salamanca.

[2] In mid-February 1809, he was promoted to Cavalry alférez[1] and later that month, at the head of 12 lancers, he captured a French convoy near Vitigudino, taking five prisoners.

[2] When General Pérez de Herrasti was given command of the garrison at Ciudad Rodrigo in October 1809,[3] Sánchez, now a lieutenant colonel, provided 240 horse for carrying out sorties.

The commanding officer of the Army of the Left, Marquis of La Romana, on recommending Sanchéz for a medal for that action, also pointed out that Sánchez had, throughout the siege, taken over 800 prisoners.

[2] Finally, given leave by Pérez de Herrasti to quit the town, on the night of 21–22 June, Sánchez crossed the bridge over the Agueda, broke through the lines of Marchand's division, and escaped to Craufurd's outpost at Almeida.

[5] That September, he fought minor actions at Barco de Ávila, Valdecasas, Muñoz and Alaejos, killing a total of 73 enemy troops and taking 32 horses.

At the same time, he was organising the 1st Regiment of Lancers and the Battalion of Castille Cazadores, formed by 1,200 men that he was able to arm, uniform and mount with the spoils of his attacks.

[1] At Wellington's behest, Sánchez stayed on the roads between Salamanca and Ciudad Rodrigo to prevent the movement of troops and convoys, sending General Erskine's Light Division and Arentschildt's brigade of cavalry up towards the Agueda, near Ciudad Rodrigo, to co-operate with the Spanish commander, the idea being that Sánchez would nofify them of the approach of any convoy and they would ford the river to intercept it.

[6] Massena's withdrawal from Portugal gave Sánchez the opportunity to attack the French columns and convoys, taking a total of 700 prisoners.

[2] During the summer of 1811, Sánchez had effectively cut communications between Ciudad Rodrigo and Salamanca, defeating any body of troops fewer than 400 men.

[2] Although provisions, escorted by a much larger force, managed to reach Ciudad Rodrigo in July, by the end of August these were again running low.

[2] Towards the end of the year, Carlos de España, sent by General Castaños to the frontier of León, to recruit men from the province of Salamanca, set up his headquarters at Ledesma.

[6] That November, the two commanders defeated the enemy forces at the action of Endrinal,[1] and Sánchez attacked a convoy, killing or wounding 80 men of the escort, at Linares de Riofrio.

[2] Sánchez formed the rearguard of Wellington's withdrawal to Portugal, and was able to prevent the capture of 1,500 fatigued Anglo-Portuguese troops that had fallen behind.

[2] Towards the end of December, and the 1st Battalion of Castille Cazadores, he attacked a column of 1,500 French troops at Vitigudino, forcing them to retreat back to Ledesma.