Why is Benedeit’s Voyage of St. Brendan significant in French literary history?

Benedeit’s Voyage of St. Brendan is significant in French literary history because it is considered perhaps the oldest purely narrative French poem written in octosyllabic couplets.1

While the original legendary tale of the saint's sea adventures, Navigatio Sancti Brendani Abbatis, was recorded in Latin prose between the 8th and 10th centuries, Benedeit’s work represents a key development in the use of the vernacular for narrative poetry within the Anglo-Norman tradition.231