The 4th Siege of Badajoz took place from July to October 1658 during the Portuguese Restoration War. It was an attempt by a huge Portuguese army under the command of Joanne Mendes de Vasconcelos, governor of Alentejo, to capture the Spanish city of Badajoz, which was the headquarters of the Spanish Army of Extremadura. The fortifications of Badajoz were essentially medieval and considered vulnerable by the Portuguese, and had already been attacked by them three times during this war.