Balbus, literally "stammerer", was a cognomen of several ancient Roman gentes. He was the second son of King Louis the Stammerer and Queen Ansgarde. Upon the death of Louis the Stammerer, however, this loyalty became largely nominal. He was the second son of Charles the Bald and brother of Louis the Stammerer. The treaty was put to the test when Louis the Stammerer died in April 879. The new king of France was his son Louis the Stammerer, formally king of Aquitaine. Louis the Stammerer was physically weak and outlived his father by only two years.