Princess Erminia was a character in the epic poem
La Gerusalemme liberata by Torquato Tasso

Torquato Tasso

Torquato Tasso was an Italian poet of the 16th century, best known for his poem La Gerusalemme liberata , in which he depicts a highly imaginative version of the combats between Christians and Muslims at the end of the First Crusade, during the siege of Jerusalem...

. In this tale she falls in love with the Christian knight

Knight

A knight was a member of a class of lower nobility in the High Middle Ages.By the Late Middle Ages, the rank had become associated with the ideals of chivalry, a code of conduct for the perfect courtly Christian warrior....

 Tancred

Tancred, Prince of Galilee

Tancred was a Norman leader of the First Crusade who later became Prince of Galilee and regent of the Principality of Antioch...

, and betrays her people to aid him. Once she discovers that Tancred is in love with Clorinde, however, she returns to join the Muslim

Muslim

A Muslim, also spelled Moslem, is an adherent of Islam, a monotheistic, Abrahamic religion based on the Quran, which Muslims consider the verbatim word of God as revealed to prophet Muhammad. "Muslim" is the Arabic term for "submitter" .Muslims believe that God is one and incomparable...

s. She subsequently steals Clorinde's armor then joins a group of shepherds.

The name Erminia is sometimes given as "Hermine". It is related to the name "Armina", the feminine form of "Armand".