An admirer of Robespierre, he was thrown into prison after the ninth of thermidor but released thanks to the intervention of his brother. In 1795 he was war commissioner to the Army of the North. Three years later he was a deputy in the Council of Five Hundred. According to the law (which required at least twenty five years) he was too young, but an exception was made for the brother of General Bonaparte, who was concluding a victorious campaign in Italy by the Treaty of Campoformio. In the assembly Louis defended the establishment of the new Cisalpine Republic, freedom of the press, crushing the jacobins, who had become his enemies. In 1799, when his brother returned from Egypt, he was president of the Council.
Lucien was the keystone of the success of the eighteenth of brumaire. He had the rumor spread of a jacobin plot, obtaining the transfer of the Chambers to Saint Cloud. Daylight having arrived, he harangued the deputies before Bonaparte entered and made a lame presentation. The deputies became heated; the coup d'etat was on the point of collapsing. Lucien laid down his presidential insignia, went out, told the astonished soldiers that the deputies had tried to assassinate his brother, mounted a horse, drew his sword, pointed it at Bonaparte and swore to run him through if he ever forsook the principles of liberty. The grenadiers, urged on by Murat, were finally convinced. They entered the hall of the Council and expelled the deputies.
At first Lucien was named minister if the interior (December 24, 1799). Affected by the death of his wife, he consoled himself by occupying himself with art and literature. He chose most of the new prefects and became involved in the affairs of the police, which displeased the minister of the police, Fouche, who showed the first consul a brochure titled 'Parallel between Caesar, Cromwell and Bonaparte', of which Lucien was probably the author. Bonaparte named a commission of inquiry, which was careful not to accuse Lucien.
Nevertheless, the two brothers quarreled. Lucien, who had himself falsified the results of the plebiscite, accused the first consul of forgetting his republican principles. Bonaparte sent him to Spain to represent France (November, 1800). Lucien won the favor of the Spanish royal family, including the favorite Godoy, with whom he signed the Treaty of Aranjuez in March of 1801. He contributed to the construction of the Kingdom of Etruria and signed other treaties, notably that of Badajoz with Portugal.
Returning to France, Lucien was reconciled with his brother, who needed his oratorical talent to make the Tribunate accept the treaty which he looked forward to signing with the Holy See. That would be the Concordat of 1801. The following year Lucien was burdened with convincing that same body that the Legion of Honor was for the people, democratic, not to say republican. As a reward Lucien was named grand officer of that new order, senator, and member of the Institute in the French language and literature section (January 26, 1803).
In his mansion in Brienne Lucien collected paintings of the masters. This admirer of Madame Recamier was familiar with Chateaubriand, Madame de Stael, Beranger, antagonists of the regime. He installed Alexandrine de Bleschamps, widow of the stockbroker Jouberthon. On May 24, 1803, she gave him a son. Lucien married her in October. Bonaparte was furious, but Lucien refused to divorce her.
Again in disgrace, Lucien settled in Italy in April of 1804 and became connected to Pope Pius VII, opposed to Napoleon. In Mantua in 1807 Napoleon offered his brother a throne in exchange for his divorce. Lucien was ready to accept if he could have total independence in the interior affairs of that hypothetical kingdom. The two brothers parted without having reached an agreement.
Pius VII made Lucien prince of Canino but in 1809 the sovereign pontiff was captured by Napoleon. Always in disgrace with the family, forbidden to stay in Rome, Lucien was on his way to the United States when his ship was captured by the English. He was briefly held at Malta, then taken to England. He was a prisoner of the English six years before Napoleon. He was assigned a residence in a village. He bought an estate and settled down.
The 1811 imperial almanac even omits him from the list of brothers of the Emperor. Lucien devoted himself to his literary work, mainly a poem about Charlemagne. Later Napoleon deplored the work, the time, the energy wasted in that opus, which he judged to be colorless, aimless, to no purpose.
In 1814, when Napoleon was Emperor of Elba, Lucien was liberated. Returned to Rome, he forgot his complaints against the fallen emperor, but he had to get away when in 1815 Murat invaded the pontifical states. In Paris he found his elder brother again and was offered the Palais-Royal. He tried without success to convince Austria to accept the abdication in favor of the king of Rome, son of Napoleon. In the last moments of the empire, after Waterloo, he found his eloquence again to plead the cause of his brother to the Tribune and the Senate. In vain.
Lucien had to flee in disguise. Recognized, he was detained in Turin by the king of Sardinia. Pius VII intervened in his favor and he returned to Italy to lead a peaceful life. He was passionate about archeological digs. In 1817 some conspirators decided to kidnap him. They invaded his house and instead ended up carrying off his secretary! They were content with a moderate ransom. Lucien died in 1841, done in by that same stomach cancer from which his father, his sister Caroline, and, so the rumor goes anyway, Napoleon himself.