Perpenna’s Defeat (72 BC) was the final battle of the Sertorian War, and saw Sertorius’s assassin defeated by Pompey after several days of skirmishing.
Perpenna had originally been a supporter of Lepidus, a failed rebel against the Sullan establishment in Rome. Perpenna had fled to Sardinia with a sizable army, and then to Spain after his position in Sardinia became too vulnerable. At first he had attempted to operate independently of Sertorius, but after Pompey was sent to Spain Perpenna’s troops forced him to operate under Sertorius. Over the next few years Perpenna had been trusted with a series of commands, and had been defeated every time he had fought. In 72 BC he finally turned on Sertorius, who had become hot tempered and suspicious, and assassinated him. Once Sertorius was dead his men suddenly realised how much they had relied on him, and turned on Perpenna. He was eventually able to take command of at least part of the army.
On the Roman side Perpenna wasn’t taken seriously as an opponent. Metellus returned to his own province in the south and west of Spain, leaving Pompey to finish off the war. Both men now wanted a battle - Pompey because he believed that Perpenna was an inferior commander, and Perpenna because he feared that he would soon lose control of his army.
For nine days the two armies skirmished, before finally they fought a full scale battle on the tenth day. Unsurprising Perpenna’s men were soon defeated all along their line, and he attempted to hide in a thicket. He was captured, and dragged to Pompey’s camp.
Frontinus reports that Pompey tricked Perperna with a feigned retreat, pulling him into an ambush. When the ambush began, the retreating troops turned around, and Perperna found that he was being attacked from both flanks and in the front. His army was slaughtered and he was captured.
Pompey was now faced with a delicate situation. Perperna claimed that he had information that would prove that many senior Romans had remained in contact with Sertorius. In order to avoid any further strife in Rome, Pompey had Perperna executed without meeting him, and then had his and Sertorius’s letters destroyed unread.
We don’t know where the battle was fought, other than it took place somewhere in Pompey’s province of Nearer Spain, in the east.