Rubuta ci gaba don wannan sakin layi - Franck ya ci gaba da rubuta waƙoƙi don mawaƙa a wannan lokacin, amma yawancin ba a taɓa buga su ba. Kamar yadda ya kasance al'ada har ma ga mawaƙa da aka horar da su a Conservatoire, bai taɓa sanin waƙar polyphonic na ƙarni na baya ba. Franck ya tsara ayyukansa na ibada a cikin salon da ake amfani da shi a lokacin, wanda Davies ya bayyana a matsayin "kiɗan duniya tare da son addini". Duk da haka, an karfafa shi ya fara aiki (1869) a kan babban aikin waƙa, "Les Béatitudes", wanda zai shafe shi fiye da shekaru goma, jinkirin da ya faru ne saboda katsewar yaƙin Franco-Prussian. Yaƙin, kamar juyin juya halin 1848
, ya sa da yawa daga cikin almajiransa suka bace, ko dai saboda sun bar Paris ko kuma an kashe su ko kuma suka nakasa a cikin fadace-fadace. Ya sake rubuta wasu wasannin kishin kasa wadanda, a cikin mawuyacin lokaci, ba a yi su ba. Shi da iyalinsa sun fuskanci wahalar tattalin arziki yayin da kuɗin da yake samu ya ragu kuma abinci da mai suka yi ƙaranci. An rufe Conservatoire don shekara ta 1870-1871. Amma canji yana zuwa yadda mawaƙa na Faransa suka ɗauki waƙar su; musamman bayan yaƙin suna neman "Ars Gallica" wanda zai zama ɗan Faransa ne. Kalmar ta zama taken sabuwar kungiyar Société Nationale de Musique, wacce Franck ta zama tsohuwar memba; waƙarsa ta bayyana a shirinta na farko a watan Nuwamba 1871.