As a result of the Treaty of Tarbes signed on 10 May 1399, John's parents were given possession of the County of Foix, but it required that his father renounce his English alliance, and it stipulated that John and one of his brothers were to be sent as hostages to the Royal Court of France to ensure observance of the terms of the treaty.
Sebagai hasil Perjanjian Tarbes yang ditandatangani pada tanggal 10 Mei 1399, orangtua Jean diberikan kepemilikan Provinsi Foix, namun diperlukan ayahandanya mengumumkan aliansi Inggrisnya, dan ditetapkan bahwa Jean dan salah satu saudaranya dikirimkan sebagai tawanan ke Istana Kerajaan Prancis untuk memastikan ketaatan dari kondisi perjanjian.