Isaak Fernand von Thurneysen
was an Imperial vice admiral who served under Reinhard von Lohengramm. They had been classmates in their youth. spoilerThurneysen, like his associate Rear Admiral Sombart, was ambitious and saw the imminent end of hostilities closing off opportunity for career advancement. As a result, he was bold and aggressive during Operation Ragnarök in order to advance his position. He participated notably in the Battle of Vermilion, where he rashly advanced his forces on his own initiative to engage Yang Wenli, who was already engaged with Brauhitch's formation. This led to confusion when Thurneysen and Brauhitch's fleets mingled, and Yang's forces took a heavy toll on the Imperial forces before order was restored and Thurneysen was ordered to withdraw by Reinhard.
Though he survived, Thurneysen fell from favour after the battle and was not seen again in active combat.