[3]: 400 Isidor was succeeded by Zadoc Kahn, who had become chief rabbi of Paris following his election to the higher post.
[4] Following the 1871 annexation of Alsace-Lorraine after the Franco-Prussian War, France lost around forty separate rabbinates in the area, resulting in a large number of unemployed rabbis throughout the country.
Isidor secured permission for the foundation of rabbinates across France to replace these missing communities: the new positions were combined with that of the hazzan due to how "unimportant" the towns were seen as being.
[3]: 403–4 Isidore was responsible for adapting the prayer in the memory of the dead which occurred at the start of Mincha on Yom Kippur.
[3]: 423 In 1882, he gave permission for Henry Joseph, an English businessman, to become chief rabbi of Argentina.