In this task, you are given a question and a context passage. You have to answer the question based on the given passage.
Q: When would all troops leave?, Context: The Prussian Army, under the terms of the armistice, held a brief victory parade in Paris on 17 February; the city was silent and draped with black and the Germans quickly withdrew. Bismarck honoured the armistice, by allowing train loads of food into Paris and withdrawing Prussian forces to the east of the city, prior to a full withdrawal once France agreed to pay a five billion franc war indemnity. At the same time, Prussian forces were concentrated in the provinces of Alsace and Lorraine. An exodus occurred from Paris as some 200,000 people, predominantly middle-class, went to the countryside.
A:
once France agreed to pay a five billion franc war indemnity