But long ere Vigilius had yielded Justinian was once more at war with Persia. When the five years’ truce ran out at the end of 549, the imperial troops advanced to recover the suzerainty of Colchis, the one point that had been yielded to Chosroes in the treaty of 545. But strangely enough, while the war was renewed on the Black Sea, it did not recommence on the Mesopotamian frontier. [Sidenote: Third Persian War, 549-55.] Both parties concurred to renew the truce for everything except Colchis, and on that limited arena alone the hostilities proceeded. The struggle recalls, in this curious feature, the way in which the French and English fought in India in the eighteenth century, while in Europe they were at peace. The conditions of the war were favourable to Justinian, whose armies had free access by sea to the Colchian coast, while the Persians had to reach it by the wild passes over the Armenian and Iberian mountains. The dreary but very bloody Colchic or Lazic war went on for six years, draining alike the Persian and the imperial treasuries; but at last the Romans had the better in the struggle, secured the homage of the Lazic king, and drove the Persians far back into the interior (555). Finally, after interminable negotiations Chosroes made peace, surrendering his claim on Colchis in consideration of an indemnity of 30,000 solidi (£18,000) per annum. This was the last of Justinian’s great wars; but the end of his reign was far from being peaceful or prosperous. It was especially noteworthy for the repeated inroads of the Huns and Slavs into the Balkan peninsula. The greatest raid was in 558, when the Cotrigur Huns under their khan Zabergan eluded the garrisons on the Danube, crossed the Balkans, and rode at large over the whole of Thrace. [Sidenote: Belisarius defeats the Huns.] One body of 4000 horse pushed their incursions up to the very gates of Constantinople, and so alarmed Justinian that he bade the aged Belisarius to buckle on his arms once more, and save the capital. The military resources of the empire were so scattered that Belisarius could only count on 300 of his own veterans, on the ‘Scholarian Guards’[13] and a levy of half-armed Thracian rustics. By skilfully posting this small force, and inducing the Huns to attack his line exactly where it was strongest, he routed the barbarians, and returned in triumph from this his last campaign. Footnote 13: A body of local troops raised in the city, who formed part of the imperial guard.