Inside the Église Saint-Paul-Saint-Louis in the Marais, you can see a curious writing on the second pillar on the right when entering the church: “République française ou la mort” (French Republic or death).
In 1871, workers took power in Paris and held it for two months, making revolutionary changes to daily life and politics in the process. For a short period, there was genuine workers’ democracy. They abolished the standing army, reduced rents, made every elected official take only the average worker’s wage, and many other things. This experience taught Karl Marx and Frederick Engels and many others a lot about the nature of the State in society, and served also as proof that socialism was possible—but the ruling class would work hard to crush it and restore their system.
We don’t know much about this revolutionary message, except that it is the work of a Communard who, hearing that the Versaillais were entering Paris, shared his republican convictions inside the church.