The III Corps approached the city on the south side of the Ebro River with the divisions of Grandjean, Antoine Morlot and Louis François Félix Musnier. At the end of December Moncey was replaced by Jean-Andoche Junot. On 10 January 1809 Grandjean's troops captured a key outwork, the San José Convent. On 22 January Marshal Jean Lannes took command of the siege from Junot. On 27 January the light companies of Grandjean's 1st Brigade successfully stormed a breach in the city walls near the Palafox Battery and Musnier's division broke into the city in another place. Ordinarily, a lodgment within a city's walls would prompt the defenders to ask for terms, but the Spanish continued to fight behind barricaded houses and churches. Lannes determined to reduce the city building-by-building if necessary. Grandjean's division stormed the Santa Monica Convent on 30 January. Two days later the French overran the adjoining San Augustin Convent after a murderous struggle amid the pews of the convent church. That day, the 44th Line broke through the defenders and advanced to the center of the city but were then driven back nearly to their starting point after losing 200 men. Henceforth, Lannes decreed that the attackers must first consolidate their gains. As the French continued to edge forward street by street, covered by their plentiful artillery, the defense finally started to collapse. On 18 February, Grandjean's division seized the University and two days later the Spanish capitulated. Since most of the fighting strength of Aragon was killed or captured in the siege, the two corps of Junot and Mortier rapidly overran the Ebro valley. Grandjean's division seized Caspe and Alcañiz before moving south as far as Morella. Badly overextended, he abandoned Morella soon after. On 5 April, Napoleon ordered Mortier's corps to withdraw from Aragon, leaving Junot's corps too weak to hold the province. On 5 May at Monzón, Spanish guerillas inflicted a defeat on one of Grandjean's brigades led by Pierre-Joseph Habert. His other brigade under Anne Gilbert de Laval was forced to relinquish Alcañiz to a Spanish army under Joaquín Blake on 19 May. On this day, Junot was replaced in command of the III Corps by Louis-Gabriel Suchet. In his first independent command, Suchet received a drubbing from Blake at the Battle of Alcañiz on 23 May 1809.