Martin captains an episode examining the life and reign of Kaiser Wilhelm II's father, Frederick III. He reigned only 99 days, but if he had lived, could he have transformed the nascent German empire from Prussian militarism to a model constitutional monarchy? Would that have transformed Europe and prevented (or mitigated) the cataclysm of World War I? 

Although they don't mention it in the episode, the guys highly recommend Our Fritz: Emperor Frederick III and the Political Culture of Imperial Germany by Frank Lorenz Muller from 2011 as an excellent source not only about Frederick's life, but also about all of the many cultural considerations that they guys discuss here as well.