In May 1648 a tax levied on judicial officers of the Parlement of Paris provoked not merely a refusal to pay but also a condemnation of earlier financial edicts and a demand for the acceptance of a scheme of constitutional reforms framed by a united committee of the parlement (the Chambre Saint-Louis), composed of members of all the sovereign courts of Paris.
The military record of the first Fronde (the Fronde Parlementaire) is almost blank. In August 1648, feeling strengthened by the news of the Prince of Condé's victory at Lens (20 August 1648), Mazarin suddenly arrested the leaders of the parlement, whereupon Paris broke into insurrection and barricaded the streets.
The noble faction demanded the calling of an assembly of the Estates General (last convoked in 1615). The nobles believed that in the Estates-General they could continue to control the bourgeois element as they had in the past.
The royal faction, having no army at its immediate disposal, had to release the prisoners and promise reforms - on the night of 22 October it fled from Paris. But France's signing of the Peace of Westphalia (Treaty of Münster, 24 October 1648) allowed the French army to return from the frontiers, and by January 1649 Condé had put Paris under siege. The two warring parties signed the Peace of Rueil (11 March 1649) after little blood had been shed. The Parisians, though still and always anti-cardinalist, had refused to ask for Spanish aid, as proposed by their princely and noble adherents under Conti, and having no prospect of military success without such aid, the noble party submitted to the government and received concessions.