Libertarianism was indeed first started by the anarcho-communist Joseph Dejacque, who described Proudhon as a "moderate anarchist, liberal, but not libertarian"[1].

But modern US-style libertarianism has one very central difference: Support for private property, which was anathema to Dejacque, who firmly supported Proudhon's infamous "property is robbery".

https://theanarchistlibrary.org/library/joseph-dejacque-on-t...