Is it ensure, insure, or assure?
sacred banner of St. Denis, late 15c., from Old French orie flambe, from Latin aurea flamma "golden flame." The ancient battle standard of the kings of France, it was of red or orange-red silk, with two or three points, and was given to the kings by the abbot of St. Denis on setting out to war. Cotgrave says it was "borne at first onely in warres made against Infidells; but afterwards vsed in all other warres; and at length vtterly lost in a battell against the Flemings." It is last mentioned in an abbey inventory of 1534.