Ratramnus was a monk at the monastery of Corbie in the ninth century who lived around the time of the Photian schism. He was commissioned by the Gallican bishops who were in turn commissioned by Pope Nicholas I to refute various accusations made by the Eastern bishops, (namely Saint Photius of Constantinople) against the Western Church. These included the inclusion of the filiqoue in the Creed, clean-shaven priests and the fact that priests were prohibited from anointing the foreheads of the baptized with chrism. The majority of the work was dedicated to the defense of the filioque, which was the second notable promotion of the innovation in the Western Church after Theodulf of Orleans had proclaimed the filioque as a dogma almost a half a century earlier. Also worth mentioning is the first major extended defense of Petrine supremacy in the Western Church, which appears towards the end of the book.
Here's a link to the original source which also contains some other translations of Latin works from the first millennium: https://github.com/wryan14/Latin-Patris ... na/vol_121