Complex sentence: Hopton was severely wounded there by the explosion of a powder-wagon and soon afterwards he was besieged in Devizes by Waller; he defended himself until relieved by the Royalist victory at Roundway Down on 13 July.
Split into simpler sentences: Hopton was severely wounded there by the explosion of a powder-wagon. Soon afterwards, he was besieged in Devizes by Waller; he defended himself until he was relieved by the Royalist victory at Roundway Down on 13 July.