It was accordingly at Byzantium that Licinius made his last desperate stand, when in A.D. 323 he found himself engaged in an unsuccessful war with his brother-in-law Constantine, the Emperor of the West. For many months the war stood still beneath the walls of the city; but Constantine persevered in the siege, raising great mounds which overlooked the walls, and sweeping away the defenders by a constant stream of missiles, launched from dozens of military engines which he had erected on these artificial heights. At last the city surrendered, and the cause of Licinius was lost. Constantine, the last of his rivals subdued, became the sole emperor of the Roman world, and stood a victor on the ramparts which were ever afterwards to bear his name. II. THE FOUNDATION OF CONSTANTINOPLE. (A.D. 328-330.) When the fall of Byzantium had wrecked the fortunes of Licinius, the Roman world was again united beneath the sceptre of a single master. For thirty-seven years, ever since Diocletian parcelled out the provinces with his colleagues, unity had been unknown, and emperors, whose number had sometimes risen to six and sometimes sunk to two, had administered their realms on different principles and with varying success. Constantine, whose victory over his rivals had been secured by his talents as an administrator and a diplomatist no less than by his military skill, was one of those men whose hard practical ability has stamped upon the history of the world a much deeper impress than has been left by many conquerors and legislators of infinitely greater genius. He was a man of that self-contained, self-reliant, unsympathetic type of mind which we recognize in his great predecessor Augustus, or in Frederic the Great of Prussia. [Illustration] Constantine the Great