Page 606

 606 A HISTORY OF THE CRUSADES II 
together to govern the island during the critical years of the Lom bard war,
and John continued, until his death in 1236, to exercise practical control
over king Henry I. 
 Politically the middle third of Henry I's long reign (1218-1 253) was dominated
by the Lombard war (1229—1243), so fateful for the Latin kingdoms in
the east. Anticipating the claims which Frederick II might raise when he
embarked on his crusade, the Ibelins had had Henry crowned in 1225, though
he did not officially come of age until 1232. The war ended, as far as opera
tions in Cyprus were concerned, in 1233, when effective imperial suzerainty
over the island ceased. 
 In the earlier years of his reign Henry was too young to play an active
role; even later on he never seems to have assumed a com manding position.
The barons of Jerusalem in 1 243 chose his mother Alice to be regent of their
kingdom until Frederick II's son Conrad should come to claim it. Henry succeeded
his mother as regent when she died in 1246, and added to his title king of
Cyprus that of lord of Jerusalem. Yet he was a singularly colorless figure.
Hill, noting that Joinville does not even mention Henry, has sug gested that
"the corpulence, which won for him the nickname of ' the Fat', may have been
connected with mental lethargy".21 
 In January 1253 Henry I died in Nicosia, leaving the kingdom to his infant
son Hugh 11(1253—1267), under the regency of his queen, Plaisance,
sister of Bohemond VI of Antioch. Seemingly it was to this young Hugh, who
did not live to attain his majority, that Thomas Aquinas dedicated the De
regimine principum.22 In 1257 Bohemond took Hugh and Plaisance to Acre, and
succeeded in having Hugh recognized as heir to the kingdom of Jerusalem,
and Plaisance as regent for her son. But her death in 1261 brought up again
the question of the regencies of both Cyprus and Jeru salem. There were at
least three possible claimants: Isabel, sister of Henry I of Cyprus, who
had married Henry of Antioch, younger son of Bohemond IV; her son, Hugh of
Antioch-Lusignan; and Hugh of Brienne, the son of her deceased elder sister
Mary and Walter of Brienne, count of Jaffa. Isabel's claim to the regency
of Cyprus was passed over by the high court in favor of a male, her son Hugh
of Antioch-Lusignan, while Hugh of Brienne, possibly in deference to his
aunt who had brought him up, did not press his claim. In Jerusalem, however,
Isabel and her husband were 
 21 Hill, History of Cyprus, II, 83; cf. 148. 
 22 See Thomas Aquinas, On the Governance of Rulers (De regimine principum)
(tr. G. B. Phelan, St. Michael's College Philosophical Texts, published for
the Institute of Mediaeval Studies, London and New York, 1938), introd.,
pp. 4, 8-11.