When France surrendered to Prussia in early 1871 the war was over and peace was finalised at the Treaty of Frankfurt on 10 May 1871. Brillouin was able to return to Paris in 1872 and, having spent the intervening time well, excelled at his studies.
Kapag France surrendered sa Prussia sa maagang bahagi ng 1871 ang digmaan ay higit at kapayapaan ay finalised sa Treaty ng Frankfurt sa 10 Mayo 1871. Brillouin ay makabalik sa Paris sa 1872, at sa pagkakaroon ng oras na ginugol sa pagitan ng mabuti, daig sa kanyang pag-aaral.