이제 李濟

Eldest son-in-law of Taejo and first-class founding subject, Lord of Heungan; killed in the First Strife of Princes; posthumous title Gyeongmu

Life & career

Yi Je (李濟, c.1365-1398) was an official of late Goryeo and early Joseon of the Seongju clan, son of Yi In-rip and grandson of Yi Jo-nyeon. He was a nephew of Yi In-im, the powerful minister under Kings Gongmin and U, and a younger cousin of Yi Jik. His birth year is uncertain and is estimated at around 1365.

Around 1383 he married Taejo Yi Seong-gye's eldest daughter, Princess Gyeongsun, and became his son-in-law. For helping his father-in-law found Joseon he was named a first-class founding subject and Lord of Heungan; the commendation document he received, Yi Je's Founding Subject Document, is National Treasure No. 324. After serving as commander of the Uihyeung Chingunwi he was promoted in 1393 to commander of the Right Army.

In the First Strife of Princes in August 1398 he was branded a follower of Jeong Do-jeon for having urged Taejo to mobilize guards against Prince Jeongan (later Taejong), and was killed with his brothers-in-law Prince Muan Bangbeon and Prince Uian Bangseok. He had no children with the princess, who became a Buddhist nun after his death. His nephew Yun (潤) became his adopted heir and ritual successor, and he is recorded with the posthumous name Gyeongmu (景武) and as enshrined in Taejo's memorial hall. The glory of Yi In-im's house thus continued through marriage into the Joseon royal family while also being cut short in the struggle for power.

National Treasure No. 324

Yi Je's Founding Subject Document is the commendation issued to him under Taejo and is designated National Treasure No. 324. The image description on Wikimedia Commons (supplied by the Cultural Heritage Administration under KOGL Type 1) presents it as National Treasure No. 324. It is a valuable record because a document received by a founding subject himself survives, but its detailed contents and place of custody could not be confirmed from this source alone.

The First Strife of Princes and His End

In the First Strife of Princes launched by Yi Bang-won in August 1398, Yi Je was branded a member of Jeong Do-jeon's faction. Wikipedia says that his advice to Taejo to mobilize guards and attack Prince Jeongan gave the pretext. He was killed together with Prince Muan and Prince Uian, and Princess Gyeongsun became a nun. He is said to have been enshrined later in Taejo's memorial hall.

Descendants

He had no children with Princess Gyeongsun, so his nephew Yun (潤) became his adopted heir. A Gyeongmu-gong branch is said to take him as central ancestor.

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