The next year, when a large French army under Marshal André Masséna invaded Portugal, Wellesley fought a delaying action at the Battle of Bussaco, before withdrawing behind the impregnable Lines, leaving Massena's army to starve in front of them. After Massena withdrew, there was fighting for most of 1811 on the frontiers of Portugal, as Wellesley attempted to recover vital fortified towns. A British and Spanish force under Beresford fought the very bloody Battle of Albuera, while Wellesley himself won the Battle of Sabugal in April, and the Battle of Fuentes de Onoro in May.