Niederhessen
But this arbitration parliament was not successful because, in parallel, the newly elected Emperor Ferdinand III, also King of Croatia, had already sent several regiments of Croatian troops to Lower Hesse to the enforce the ban against William V. During their campaign the Croats devastated large parts of Lower Hesse and also threatened to take Cassel. In this situation, William V fled with his family and a large part of his army to East Frisia, where he was granted refuge by Ulrich II of East Frisia following mediation by the states-general. There, in the encampment at Leer, he died from disease on 21 September 1637.