About the name there are two opposite explanations: from the Latin sol opacus, that is a place with little sun, or from sub pago, the village that lies below — below the massif of the Taburno. The built-up area is narrow and long, a kilometre and a half stretched along the foot of the mountain, with the Calore marking its northern edge. The first mentions come from just before the thirteenth century: in 1198 the register of the dead of a confraternity in Benevento records the death of «Petrus marandu de Casali Sancti Johannis de Surrepaca», and another in 1208. Historians hold that Solopaca was born as a hamlet of Telesia after the Saracen raids and the earthquake of the middle of the ninth century had devastated that city; the Statutes of Telese support it, written between 1197 and 1250 by the notary Antonello of Cerreto Sannita, which list the dependent hamlets and among them «Sorropache». Later, when the earthquake of 1349 opened mofettes and sulphurous exhalations and Telese emptied for good, its refugees came here: one of the quarters of the town is still called Telesini, and in the church of San Mauro there is an old sculpture of the saint that those refugees carried with them.
In 1268 Charles the First of Anjou gave Solopaca and Telese to Guglielmo Belmonte, grand admiral of the kingdom. From 1487 the town belonged to the Lagonessa and from 1574 to the Ceva Grimaldi, who governed it for two centuries by terror: arbitrary searches and imprisonments, corrupted municipal magistrates, tortures and corporal punishments. In 1662 duke Antonio Ceva Grimaldi lost his emerald ring and threw the town into alarm; a passing merchant, Pompeo Petrucci, found it and brought it back to him, and instead of thanking him the duke ordered that he be given «a thousand blows on naked flesh». In 1727 a woman, after inhuman tortures by the ducal guards, was forced to declare herself guilty of a crime she had nothing to do with. The earthquake of 5 June 1688 meanwhile did enormous damage. The last feudal lords were the di Sangro, until feudalism was abolished in 1806; in 1835 king Ferdinand the Second came in person to inaugurate the Maria Cristina bridge. Until 1934, finally, the municipal territory was far larger and included Telese Terme as well.