John of Brienne

John of Brienne (c. 1170 – 19–23 March 1237) was the king of Jerusalem from 1210 to 1225 and Latin emperor of Constantinople from 1229 to 1237. He was the youngest son of Erard II of Brienne, a wealthy nobleman in Champagne. John, originally destined for an ecclesiastical career, became a knight and owned small estates in Champagne around 1200. After the death of his brother Walter III, he ruled the County of Brienne on behalf of his minor nephew Walter IV, who lived in Italy.

The barons of the Kingdom of Jerusalem proposed that John marry their queen, Maria. With the consent of Philip II of France and Pope Innocent III, he left France for the Holy Land and married Queen Maria; the couple were crowned in 1210. After Maria's death in 1212 John administered the kingdom as regent for their infant daughter Isabella II; Maria's influential uncle, John of Ibelin, attempted to depose him. King John was a leader of the Fifth Crusade. Although his claim of supreme command of the crusader army was never unanimously acknowledged, his right to rule Damietta (in Egypt) was confirmed shortly after the city fell to the crusaders in 1219. He claimed the Armenian Kingdom of Cilicia on behalf of his second wife, Stephanie, in 1220. After Stephanie and their infant son died that year, John returned to Egypt. The Fifth Crusade ended in failure (including the recovery of Damietta by the Egyptians) in 1221.

John was the first king of Jerusalem to visit Europe (Italy, France, England, León, Castile and Germany) to seek assistance for the Holy Land. He gave his daughter in marriage to Holy Roman Emperor Frederick II in 1225, and Frederick ended John's rule of the Kingdom of Jerusalem. Although the popes tried to persuade Frederick to restore the kingdom to John, the Jerusalemite barons regarded Frederick as their lawful ruler. John administered papal domains in Tuscany, became the podestà of Perugia and was a commander of Pope Gregory IX's army during Gregory's war against Frederick in 1228 and 1229.

John was elected emperor of the Latin Empire in 1229 as the senior co-ruler of Baldwin II, and he was crowned in Constantinople in 1231. John III of Nicaea and Ivan Asen II of Bulgaria occupied the last Latin territories in Thrace and Asia Minor, besieging Constantinople in early 1235. John directed the defence of his capital during the months-long siege, with the besiegers withdrawing only after Geoffrey II of Achaea and united fleets from Italian towns defeated their fleet in 1236. The following year, John died as a Franciscan friar.

John was the youngest of the four sons of Count Erard II of Brienne and Agnes of Montfaucon. He seemed "exceedingly old ... about 80" to the 14-year-old George Akropolites in 1231; if Akropolites' estimate was correct, John was born around 1150. However, no other 13th-century authors described him as an old man. John's father referred to John's brothers as "children" in 1177 and mentioned the tutor of the oldest brother, Walter, in 1184; this suggests that John's brothers were born in the late 1160s. Modern historians agree that John was born after 1168, probably during the 1170s.

John's father destined him for a clerical career, but according to the late-13th-century Tales of the Minstrel of Reims he "was unwilling". Instead, the minstrel continued, John fled to his maternal uncle at the Clairvaux Abbey. Encouraged by his fellows, he became a knight and earned a reputation in tournaments and fights. Although elements of the Tales of the Minstrel of Reims are apparently invented (for instance, John did not have a maternal uncle in Clairvaux), historian Guy Perry wrote that it may have preserved details of John's life. A church career was not unusual for youngest sons of 12th-century noblemen in France; however, if his father sent him to a monastery he left before reaching the age of taking monastic vows. John "clearly developed the physique that was necessary to fight well" in his youth, because the 13th-century sources Akropolites and Salimbene di Adam emphasize his physical strength.

John's father, Erard II, joined the Third Crusade and died in the Holy Land in 1191. His oldest son, Walter III, succeeded him in Brienne. John was first mentioned in an 1192 (or 1194) charter issued by Walter, indicating that he was a prominent figure in his brother's court. According to a version of Ernoul's chronicle, John participated in a war against Peter II of Courtenay. Although the Tales of the Minstrel of Reims claimed that he was called "John Lackland", according to contemporary charters John held Jessains, Onjon, Trannes and two other villages in the County of Champagne around 1200. In 1201, Theobald III of Champagne granted him additional estates in Mâcon, Longsols and elsewhere. Theobald's widow, Blanche of Navarre, persuaded John to sell his estate at Mâcon, saying that it was her dower.

Walter III of Brienne died in June 1205 while fighting in southern Italy. His widow, Elvira of Sicily, gave birth to a posthumous son, Walter IV, who grew up in Italy. John assumed the title of count of Brienne, and began administering the county on his nephew's behalf in 1205 or 1206. As a leading vassal of the count of Champagne, John frequented the court of Blanche of Navarre, who ruled Champagne during the minority of her son, Theobald IV. According to a version of Ernoul's chronicle, she loved John "more than any man in the world"; this annoyed King Philip II of France.