Haven't really done much on the German army of this period - so a few posts to try and rectify this.
According to the wiki
Bavarian army in the Franco-Prussian war
When the candidacy to the Spanish throne of Leopold, Prince of Hohenzollern led to a worsening in relations between Prussia and France in 1870, von Prankh mobilised the two Bavarian army corps on 14 July. The Bavarian Army Corps fought in the Franco-Prussian War as part of the III Army under Crown Price Friedrich Wilhelm (the I Army Corps under von der Tann, and the II Army Corps under von Hartmann).