8 – John I (1229 – 1237)
Although Robert’s youngest brother, Baldwin II, was his successor, the child of Peter II of Courtenay was only 10 years of age, so yet another regent had to be found to rule on his behalf. Ivan Asen II offered his services, but unsurprisingly, the barons refused his approach and chose the former King of Jerusalem, John of Brienne, as the new monarch.
When John became the new emperor, his main threat came from Theodore Doukas who was almost in sight of Constantinople in 1230. However, he believed that Ivan Asen would become the new ruler of the Latin Empire and considered Bulgaria the only threat remaining to his conquest. As a result, he invaded Bulgaria in 1230 without a declaration of war and plundered villages along the way. He was so confident of victory that he brought his entire court including his wife and children. However, disaster struck at the Battle of Klokotnista on March 9, 1230, when he lost most of his army and died on the battlefield along with his court.
The Bulgarian Empire was soon expanded in a lightning campaign and in 1235, Asen joined forces with John III of Nicaea. Together, they started to besiege Constantinople but were defeated in 1236 when Venetian ships came to the aid of the city. John distinguished himself during the siege and was praised for his bravery. However, the Latin Empire had lost its last outposts in Asia Minor and Gallipoli while its territories in Thrace fell to the Bulgarians.
Three authors from the thirteenth-century claim that John became a Franciscan friar sometime in 1237; possibly due to his failing health. Certainly, Baldwin II had reached the age of succession by this stage, so it made sense for John to step aside after saving Constantinople. John died at some stage between 19-23 March 1237 and had the distinction of being the only Latin Emperor to die in Constantinople.