Final answer:
The interaction between armies can vary depending on the context. In the cases of the Franco-Prussian War and World War I, Paris was directly affected by the movements of the armies involved.
Step-by-step explanation:
The interaction between armies can vary depending on the specific historical context. In the case of Paris, it has been involved in several conflicts throughout history. For example, during the Franco-Prussian War in 1870 and 1871, Paris was besieged by the Prussian army. Additionally, during World War I, German armies were moving towards Paris, but the French were able to stop their advance during the Battle of the Marne. In both cases, the armies played a significant role in the outcome of the conflicts and the fate of Paris.