Back then wars were fought very differently than later. Rather than wars of otrition those wars were marked by a few decisive battles which had the goal of annihilating as much of the enemy army as possible (either literally or by taking them prisoner). This search for the decisive victory lead to wars being fairly short, meaning that there wasn’t a real wartime economy since the time of war was rather short. In the franco-prussian war the speed of mobilisation prooved more decisive than the wartime economy since the decisive battle of sedan happened barely two months into the war. This dynamic changed with the uprising of nationalism and social darwinism. As war evolved from the continuation of politics by different means to a battle of morale and people vs people as well as the evolution of war machinery (machine guns for instance) wars became wars of otrition (i.e. the american civil war which was fought much more „modern“ than the franco-prussian war despite preceding it. In a war that lasts ceveral years wartime economy becomes the decisive factor due to the sheer effort it takes to provide for an army for that timespan.