further anarchy he was succeeded by John Asen II.  During the reign of this monarch, which lasted from 1218 till 1241, Bulgaria reached the zenith of its power.  He was the most enlightened ruler the country had had, and he not only waged war successfully abroad but also put an end to the internal confusion, restored the possibility of carrying on agriculture and commerce, and encouraged the foundation of numerous schools and monasteries.  He maintained the tradition of his family by making his capital at Tirnovo, which city he considerably embellished and enlarged.

Constantinople at this time boasted three Greek emperors and one French.  The first act of John Asen II was to get rid of one of them, named Theodore, who had proclaimed himself basileus at Okhrida in 1223.  Thereupon he annexed the whole of Thrace, Macedonia, Thessaly, and Epirus to his dominions, and made Theodore’s brother Manuel, who had married one of his daughters, viceroy, established at Salonika.  Another of his daughters had married Stephen Vladislav, who was King of Serbia from 1233-43, and a third married Theodore, son of the Emperor John III, who reigned at Nicaea, in 1235.  This daughter, after being sought in marriage by the French barons at Constantinople as a wife for the Emperor Baldwin II, a minor, was then summarily rejected in favour of the daughter of the King of Jerusalem; this affront rankled in the mind of John Asen II and threw him into the arms of the Greeks, with whom he concluded an alliance in 1234.  John Asen II and his ally, the Emperor John III, were, however, utterly defeated by the French under the walls of Constantinople in 1236, and the Bulgarian ruler, who had no wish to see the Greeks re-established there, began to doubt the wisdom of his alliance.  Other Bulgarian tsars had been unscrupulous, but the whole foreign policy of this one pivoted on treachery.  He deserted the Greeks and made an alliance with the French in 1237, the Pope Gregory IX, a great Hellenophobe, having threatened him with excommunication; he went so far as to force his daughter to relinquish her Greek husband.  The following year, however, he again changed over to the Greeks; then again fear of the Pope and of his brother-in-law the King of Hungary brought him back to the side of Baldwin II, to whose help against the Greeks he went with a large army into Thrace in 1239.  While besieging the Greeks with indifferent success, he learned of the death of his wife and his eldest son from plague, and incontinently returned to Tirnovo, giving up the war and restoring his daughter to her lonely husband.  This adaptable monarch died a natural death in 1241, and the three rulers of his family who succeeded him, whose reigns filled the period 1241-58, managed to undo all the constructive work of their immediate predecessors.  Province after province was lost and internal anarchy increased.  This remarkable dynasty came to an inglorious end in 1258, when its last representative was murdered by his own nobles, and from this time onwards Bulgaria was only a shadow of its former self.