 This paved the way for the siege, which started when Ramón de Bonifaz sailed with thirteen galleys, accompanied by some smaller ships, up the Guadalquivir and scattered some forty smaller vessels trying to oppose him.On 3 May the Castilian fleet broke the pontoon bridge linking Seville and Triana.St Albertus Magnus wrote that the Moorish defenders used artillery which was loaded with rocks in the siege, but this is not certain that is describing the type of firearms.