In 1227-28 the Emperor Frederick II undertook the sixth crusade, landing at Acre in the latter year, and being crowned King of Jerusalem in 1229. Within thirty years from these dates the symbol appeared on the coins of certain Flemish princes, and in 1345 it replaced the single-headed eagle on the armorial bearing of the holy Roman Empire. Thus, the historic evidence of the migration of this symbol, from the far east to the nations of the west by direct contact, would seem complete. _The lion rampant of Belgium._--This lion was incorporated into the Percy or Northumberland escutcheon by the marriage of Joceline of Louvain, the second son of Godfrey, the Duke of Brabant, to Agnes, the sister and heir of all the Percys. The Counts of Flanders, Brabant, and Louvain bore as their coat of arms the lion rampant facing to the left, which is the present coat of arms of the King of Belgium. The story is thus told in Burke's "Peerage" (1895): Agnes de Percy married Joceline of Louvain, brother of Queen Adeliza, second wife of Henry I, and son of Godfrey Barbalus, Duke of Lower Brabant and Count of Brabant, who was descended from the Emperor Charlemagne. Her ladyship, it is stated, would only consent, however, to this great alliance upon condition that Joceline should adopt either the surname or arms of Percy, the former of which, says the old family tradition, he accordingly assumed, and retained his own paternal coat in order to perpetuate his claim to the principality of his father, should the elder line of the reigning duke become extinct. The matter is thus stated in the old pedigree at Sion House: "The ancient arms of Hainault this Lord Jocelyn retained, and gave his children the surname of Percy."