The VI Corps was heavily engaged at the Battle of Bussaco on 27 September 1810. Loison's division suffered 1,252 casualties, including brigade commander Édouard François Simon who was captured. Marchand's division lost an additional 1,173, while General Julien Augustin Joseph Mermet reported only 24 casualties. During the retreat from Portugal, Ney directed several rear guard actions at Pombal, Redinha, Casal Novo, and Foz do Arouce between 11 and 15 March 1811. A week later, Ney flatly refused to obey a direct order resulting in his dismissal by Marshal André Masséna. Loison led the corps at the Battle of Fuentes de Onoro and General Claude François Ferey took command of Loison's division. In the fighting on 3 May, Ferey's and Marchand's divisions suffered 652 casualties, including 76 killed, 409 wounded, and 167 missing. On 5 May, all three divisions lost 107 killed, 804 wounded, and 33 missing. Soon after the battle, the new army commander Marshal Auguste de Marmont dissolved the corps organizations, including the VI Corps. Among others, Marchand and Mermet were sent home.