Gerlach IV of Isenburg-Limburg

Gerlach was the son of Henry (Heinrich) I of Isenburg-Grenzau and his wife, Irmingard of Büdingen, Countess of Cleeberg (now part of Langgöns).

From a trip to Italy in 1231, Gerlach brought monks of the Franciscan Order to whom he gave permission to construct a monastery in Limburg.

Upon his return, Gerlach expanded Limburg Castle, building the residential tower which is still extant today.

To secure his position, Gerlach sought dynastic connections with neighboring lordly houses, including Nassau, Westerburg, and Diez.

Gerlach I of Limburg died in 1289 during his participation in a campaign of King Rudolph in the Black Forest.