During the 18th and 19th centuries the city became an important industrial centre and saw its size and population increase. The invasion of the Napoleonic troops in Portugal under Marshal Soult is still vividly remembered in Porto. A day after the French victory at the First Battle of Porto, on 29 March 1809, as the population fled for the advancing troops and tried to cross the river Douro over the Ponte das Barcas (a pontoon bridge), the bridge collapsed under the weight. Possibly 6,000 people drowned in the disaster. This event is still remembered by a plate at the Ponte D. Luis I. The French army was rooted out of Porto by Anglo-Portuguese forces commanded by Arthur Wellesley in the Second Battle of Porto, when his troops crossed the Douro river from the Mosteiro da Serra do Pilar (a former convent) in a brilliant daylight coup de main.