The Congress of Vienna, which addressed the problem of Christian slaves from Barbary piracy, charged the United Kingdom and the Netherlands to negotiate with the Dey of Algiers and the Beys of Tunis and Tripoli. Although the latter two were agreeable, Omar Agha was not. It would take the 9-hour Bombardment of Algiers (1816) on 27 August 1816, by an Anglo-Dutch naval force commanded by British Admiral Lord Exmouth, to compel the Dey to abolish Christian slavery. However, the bombardment of Algiers did not destroy Barbary power. Despite the signing of the treaty and the release of 3,000 christian slaves, Dey Omar set to rebuilding the city's defences, putting its Jewish inhabitants to forced labour in the place of Christian slaves. Moreover, the problem remained such that it was one of the main areas of contention at the Congress of Aix-la-Chapelle (1818).