I opened up the save and took a look around. Having the Buddhist Holy City allows us to view Bismarck's troop deployments, and here is what we see:
Bismarck has a total of 6 Knights, 1 Horser Archer and a Pikeman that he can throw at Hamburg in the IBT. (The is another Knight in Frankfurt to the SW.) As you can see, aside from Munter's inspired Guerrila II promoted Longbow, Hamburg is pretty lightly defended. I could move the anti-Horse Phalanx to the SW into the city in an attempt to hold it, but that would mean the certain defeat of our weakened CR Macemen there. Doing so, however,
*might* allow us to continue the war and attempt to take either Dortmund to the NW or Franfurt to the SW. Frankfurt, in particular, would be a good addition to our empire, as it would definitely reduce the German cultural pressure on Hamburg and would give us, finally, access to Horses (more about that below). If we don't claim Frankfurt, and end the war now, we may lose Hamburg to cultural pressure anyway.
So the question is, do we end the war now, or let the dice roll and hope that we can hold off Bismarck's counterattack?
Here is Bismarck's best offer:
Unfortunately, he is not willing to give us any techs.
Regarding Horses, some are still unclaimed in the West. Mao, however, already has one settlement there and he or Genghis will probably plant another one to claim the Horses within the next 10-15 turns. If it's Genghis, no problem, but if it's Mao, we could be in for another war to claim them.