Kammala jumla mai zuwa: Bayan hauhawar Countess Amalie Elisabeth zuwa kursiyin a watan Satumba na 1637, Geyso ya sami rawar gani sosai a cikin kamfen din soja na Langravate a kan kishiyar Landgraviate na Hesse-Darmstadt. A cikin kaka na 1641, ya yi umurni da kare Dorsten a ƙarshe ya ba da shi ga Darmstadt a kan yanayi mai kyau. A shekara ta 1644, an kira shi da marshal na Sweden Lennart Torstensson wanda ya nemi taimakonsa tare da kewaye sojojin sojojin Matthias Gallas wanda a lokacin yana aiki a kusa da Magdeburg. Maza 2,300 na Geyso sun shiga cikin tafiya mai wahala ta cikin yankunan da ke ambaliyar ruwa, sun isa kan lokaci don ganin rushewar sojojin Imperialist. A ranar 3 ga Agusta, 1645, ƙarfin hali na Hessians ya ba da gudummawa ga nasara a
Yaƙin Nördlingen (1645).