In 1239, Hugh joined the Barons' Crusade led by King Theobald I of Navarre and supported by Frederick II, Holy Roman Emperor.

Realizing that the expedition was disadvantageous, he opted to withdraw to Ascalon with Walter IV, Count of Brienne and a few others, avoiding the disastrous battle of Gaza.

In 1266, he met with Baldwin II, Latin Emperor, who sold Hugh the title of king of Thessalonica in exchange for reconquering his lost domains.

The sale would only remain valid until Hugh aided in Baldwin's reconquest and should he fail to uphold his end, the title would pass to Charles I of Anjou and his heirs.

The invasion wouldn't come to pass, as Pope Gregory X, under the false promise of Emperor Michael VIII Palaiologos to unite the churches, staved off any attempts.