Henry of Flanders Henry ( 1174 ? – 1216 ? ) was the second emperor of the Latin Empire of Constantinople . He was a younger son of Baldwin V , Count of Hainaut ( later Baldwin VIII , count of Flanders ) , and Margaret I of Flanders , sister of Philip of Alsace , count of Flanders . Leadership in the Fourth Crusade . Having joined the Fourth Crusade in about 1201 , he distinguished himself at the sieges of Constantinople and elsewhere . During the July 1203 siege , Henry was one of eight division generals , the others including Boniface of Montferrat ( the crusade leader ) , Doge Enrico Dandolo ( leader of the Venetians ) , Louis of Blois ( one of the first nobles to take the cross ) , and Henry ' s own brother , Baldwin of Flanders , who controlled the largest division . During the 1204 siege , Henry led a chevauchée expedition to gain supplies and raided a castle in Philia , near the Black Sea with , according to Robert de Clari , about 30 knights and an unspecified number of mounted sergeants . An ambush was laid for him by Emperor Alexius V " Murzuphlus " Ducas , but Henry and his force routed the Greeks soundly , captured a revered icon supposedly containing relics of Christ , and returned to the crusader camp . He soon became prominent among the princes of the new Latin Empire . In the Latin Empire . When his elder brother , the emperor Baldwin I , was captured at the Battle of Adrianople in April 1205 by the Bulgarians , Henry was chosen regent of the empire , succeeding to the throne when the news of Baldwin ’ s death arrived . He was crowned 20 August 1206 . Henry was a wise ruler , whose reign was largely passed in successful struggles with Kaloyan , Tsar of Bulgaria , and with his rival , Theodore I Lascaris , emperor of Nicaea . He later fought against Boril of Bulgaria ( 1207 – 1218 ) and managed to defeat him the Battle of Philippopolis . Henry campaigned against the Nicean Empire , expanding a small holding in Asia Minor ( at Pegai ) with campaigns in 1207 ( at Nicomedia ) and in 1211 – 1212 ( with the Battle of the Rhyndacus ) , where he captured important Nicean possessions at Nymphaion . Though Theodore I Laskaris could not oppose this later campaign , it appears that Henry decided it best to focus on his European problems , for he sought a truce with Theodore I in 1214 , and amicably divided Latin from Nicean possessions to the favour of Nicea . Domestically , Henry appears to have a different character than many of the other Crusader nobles as seen in his even - handed and pragmatic treatment of the Greeks . George Akropolites , the contemporary 13th century Greek historian , notes that Henry " though a Frank by birth , behaved graciously to the Romans who were natives of the city of Constantine , and ranked many of them among his magnates , others among his soldiers , while the common populace he treated as his own people . " Indeed , when a Papal legate ( Pelagio Galvani , Cardinal Bishop of Albano ) arrived in Constantinople in 1213 and began to imprison Orthodox clergy and to close churches on the orders of Pope Innocent III , Henry countermanded the orders on the request of the city ' s Greek clergy . Henry appears to have been brave but not cruel , and tolerant but not weak , possessing " the superior courage to oppose , in a superstitious age , the pride and avarice of the clergy . " The emperor died , poisoned , it is said , by Oberto di Biandrate , ex - regent of Thessaloniki , on 11 June 1216 . Gardner suggests this happened at the instigation of his Bulgarian wife Maria of Bulgaria . On his death his nephew Peter was crowned Emperor in Rome , but never arrived in Constantinople . In the years 1217 to 1219 , therefore , the Latin Empire was effectively ruled by Iolanda , Henry ' s sister and Peter ' s mother , in regency . Family . Henry first married ( in 1204 ) Agnes of Montferrat , daughter of Boniface of Montferrat , the Crusade leader , but she had died ( probably in childbirth ) before her father ' s death in 1207 . Henry ' s only child by his first wife Agnes apparently died in childbirth with his mother Some contemporary historians say that Henry made a peace with Bulgarians after the death of Kaloyan , and a marriage was arranged in 1213 between Henry and Maria of Bulgaria , daughter of Kaloyan and stepdaughter of Boril , Tsar of Bulgaria . Henry had a daughter with an unnamed mistress . This daughter , whose name is not recorded , later married Alexii Slav who established his own state in the Rodophe mountains . He was later given the title of despot .