John I of Nassau-Weilburg

John I of Nassau-Weilburg (1309–1371) was Count of Nassau-Weilburg from 1355 to 1371.

John I was the second son of Count Gerlach I of Nassau-Wiesbaden and Agnes of Hesse, granddaughter of Henry I, Landgrave of Hesse. On Gerlach I abdication in 1346, John and his brothers divided the family lands. John acquired Weilburg on the Lahn.

John was adopted by Emperor Charles IV in 1366 and elevated to Imperial Count. He died on September 20, 1371.

John I was married twice. His first marriage in 1333 was to Gertrude of Merenberg (d. 1350), daughter and heiress of Hartrad, the last Lord of Merenberg and Gleiberg. Gertrude died on October 6, 1350 and was buried in Weilburg. The couple had one child, a daughter. She was engaged in 1340 with Reinhard II of Westerburg, but died shortly thereafter.

John I's second marriage in 1353 was to Johanna of Saarbrücken, Dame de Commercy and heiress of Count John II of Saarbrücken. This union produced seven children:

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