What council was held in Rome in 378? And I assume you mean Pope Damasus, not Damascus?
Spell correction is a pain. But to answer you question:
"This synod is distinct from the more famous Council of Rome in 382 AD (also under Damasus), which is traditionally associated with discussions on the biblical canon and doctrinal matters following the First Council of Constantinople (381 AD). Some sources refer to a doctrinal "tome" (statement) issued by Damasus and a Roman council around 378, which influenced Eastern churches on Trinitarian theology against Arian-related heresies."
"The Tome of Damasus refers to a significant theological document and collection of 24 canons issued by Pope Damasus I and endorsed by a Synod of Rome (historically dated between 377 and 382 AD, with the formulas specifically accepted by the East in 379).
It served as a definitive response to prevalent 4th-century heresies and a strong assertion of Roman papal authority. Key aspects include:
Anti-Heretical Focus: The Tome was primarily directed against Arianism (which denied the full divinity of Christ) and Apollinarianism (which denied Christ had a human soul).
Trinitarian Doctrine: It solidified the Western Church's stance on the Trinity, emphasizing that the Father, Son, and Holy Spirit are of one substance.
Papal Primacy: The Tome and its associated synods marked the first time the Roman See was officially referred to as the "Apostolic See". It asserted that Rome’s primacy came from the authority of St. Peter rather than imperial or synodal decrees.
Historical Context (379 AD): In 379, the Council of Antioch formally accepted the doctrinal formulas contained in Damasus's Tome, signaling a rare moment of theological alignment between the Western and Eastern churches during the Trinitarian controversies.'
"In October 379, the Council of Antioch (also referred to as a "great synod") was a significant gathering of 153 Eastern bishops. Presided over by Meletius of Antioch, the council marked
a critical turning point in the restoration of Nicene Orthodoxy following the death of the Arian Emperor Valens and the accession of Theodosius I.
Key Outcomes and Significance
Establishment of Doctrinal Unity:
The council formally accepted the "Tome of the Westerns" (a dogmatic letter from Pope Damasus I and the Western bishops), thereby establishing doctrinal agreement between the Eastern and Western churches regarding the Holy Trinity.
Restoration of Orthodoxy: It served to consolidate the "Neo-Nicene" position in the East, effectively ending the dominance of Arianism in the region.
Settling the Meletian Schism: The council attempted to resolve the long-standing schism in Antioch between the supporters of Meletius and Paulinus. A temporary agreement was reached where leading presbyters vowed not to seek episcopal consecration, instead agreeing to follow whichever rival bishop survived the other.
Prelude to the Second Ecumenical Council: The 379 synod laid the groundwork for the First Council of Constantinople in 381, where Meletius would also preside before his death.
Support for Gregory of Nazianzus: The council supported the appointment of Gregory of Nazianzus to the see of Constantinople, a move crucial for the upcoming ecumenical deliberations."