E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
Montjoie St. Denis.
The war-cry of the French. Montjoie is a corruption of Mons Jovis, as the little mounds were called which served as direction-posts in ancient times; hence it was applied to whatever showed or indicated the way, as the banner of St. Denis, called the Oriflamme. The Burgundians had for their war-cry, Montjoie St. André; the dukes of Bourbon, Montjoie Notre Dame; and the kings of England used to have Montjoie St. George. There seems no sufficient reason to suppose that Montjoie St. Denis is a corruption of St. Denis mon joiei.e. St. Denis is my hope.
Montjoie. The cry of the French heralds in the ancient tournaments; and the title of the French king-of-arms.