Anglo-German War, 1871: what if scenario

One of the interesting situations that I learned about during my time at the Halifax citadel was that the British army began to withdraw to the Home front due to the increased power of Prussia soon to be Germany.
At the time, an interest in invasion fiction hit the western world as an interesting genre of pop culture.
Another chance for me to use my Napoleonic cavalry and Colonial troops plus first war Germans and French.
Inspired by August 2019 issue of Wargames illustrated