Conversation so far:
when did germany takes alsace-lorraine region from france in the franco-prussian war
The Treaty of Frankfurt of 10 May 1871 gave Germany most of Alsace and some parts of Lorraine, which became the Imperial territory of Alsace-Lorraine.
how long was the franco-prussian war
The Franco Prussion War was 6 months, 1 week and 2 days.

Question: when did the war happen
Self-contained rewrite: when did the franco-prussian war happen