After the Battle of Crecy, the French defences in the southwest were left both weak and disorganised. Lancaster took advantage by launching offensives into Quercy and the Bazadais and himself leading a third force on a large-scale mounted raid (a chevauchée) between 12 September and 31 October 1346. All three offensives were successful, with Lancaster's chevauchée, of approximately 2,000 English and Gascon soldiers, meeting no effective resistance from the French, penetrating 160 miles (260 kilometres) north and storming the rich city of Poitiers. His force then burnt and looted large areas of Saintonge, Aunis and Poitou, capturing numerous towns, castles and smaller fortified places as they went. The offensives completely disrupted the French defences and shifted the focus of the fighting from the heart of Gascony to 50 miles (80 kilometres) or more beyond its borders. He returned to England in early 1347.