Discords arose between the Vatican and the French Republic, and it is clear that Napoleon and the French Directory ordered Joseph to encourage revolutionary movements in Rome. On the 28th of December 1797 a disturbance took place opposite the French embassy, which led to the death of the French general, Leonard Duphot. Joseph at once left Rome, which soon became a republic. Repairing to Paris, he entered on parliamentary life, becoming one of the members for Corsica in the Council of Five Hundred. He made no mark in the chamber and retired in 1799. Before the _coup d'etat_ of Brumaire he helped Napoleon in making overtures to Sieyes and Moreau, but otherwise did little. Thereafter he refused to enter the ministry, but became a member of the council of state and of the _Corps Legislatif_, where his advice on the state of public opinion was frequently useful. He had a hand in the negotiations for the Concordat, but, according to Lucien Bonaparte, looked on that measure as "ill-advised and retrograde." His services in the diplomatic sphere were more important. At Mortfontaine, his country-house, he concluded with the envoy of the United States a convention which bears that name (1800). He also presided over the negotiations which led to the treaty of Luneville with Austria (February 9, 1801); and he and Maret represented France in the lengthy discussions with the British envoy, Lord Cornwallis, which resulted in the signature of the treaty of Amiens (March 25, 1802). This diplomatic triumph in its turn led to the consolidation of Napoleon's power as First Consul for life (August 1, 1802) with the chief voice in the selection of his successor. On this question the brothers disagreed. As neither Joseph nor Napoleon had a male heir, the eldest brother, whose ideas of primogeniture were very strict, claimed to be recognized as heir, while Napoleon wished to recognize the son of Louis Bonaparte. On the proclamation of the French empire (May 1804) the friction became acute. Napoleon offered to make Joseph king of Lombardy if he would waive all claim of succession to the French throne, but met with a firm refusal.