And the military campaigns that now began were among the most brilliant in the world’s history. Arabia had suddenly become a garden of fine men. The name of Khalid stands out as the brightest star in a constellation of able and devoted Moslem generals. Whenever he commanded he was victorious, and when the jealousy of the second Caliph, Omar, degraded him unjustly and inexcusably, he made no ado, but served Allah cheerfully and well as a subordinate to those over whom he had ruled.