Complex sentence: The Battle of Tryfrwyd (or Tribruit) was the tenth battle fought by Arthur as "Dux Bellorum", mentioned in a number of early Welsh sourcers including the eleventh century poem "Pa Gur" and the works of the historian Nennius.
Split into simpler sentences: The Battle of Tryfrwyd (or Tribruit) was the tenth battle. ' fought by Arthur as "Dux Bellorum", mentioned in a number of early Welsh sourcers including the eleventh century poem "Pa Gur" and the works of the historian Nennius.