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 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.

[8] A two-year war ensued and after defeating the Templar-supported Lombards, Henry confiscated the Templar castles of Ravennika and Zetouni (Lamia).

[9] Henry was a wise ruler, whose reign was largely passed in successful struggles with Tsar Kaloyan of Bulgaria and with his rival Emperor Theodore I Lascaris of Nicaea.

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.

[14] 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.