The Treaty of Ribemont was signed on 2 May 1179 by the two eldest sons of the late Duke Matthias I of Lorraine. Matthias had died in 1176, without having laid down plans for his succession,^[1] and his duchy was claimed by his eldest son, Simon, and his second son, Frederick. In 1178 civil war broke out between the brothers.^[2] Through the mediation of Count Philip of Flanders the next year, the brothers were able to reach an agreement at Ribemont to partition the duchy. Simon received the southern, French-speaking part of the duchy, and Frederick received the northern, German-speaking part plus Ormes and Gerbéviller. Frederick also pledged himself to be his brother's vassal, but he employed the title "Duke of Bitche", an expression of equal status.^[2]

In 1206 Simon abdicated and the duchy was reunited in the hands of his brother, as per the treaty of 1179.^[3]