Forced into exile during the restoration of 1791, he moved to
Lille in January, then to Paris, where he maintained some activity on account on the defunct
Republic of Liège, such as develop with other exiles a draft constitution proclaiming the equality of all citizens, freedom of the press and the formation of an assembly where national bourgeois representation would count twice as large as those of the clergy and nobility, or on 18 December appearing before the
Legislative Assembly at the head of a Liège delegation. However, he rapidly got engrossed in French Revolution politics through his newspaper he had revived starting March 1791. This got him in acquaintance with forefront players of those days, such as
Jacques-Pierre Brissot,
Etienne Claviere,
Jean-Marie Roland and
Charles François Dumouriez; Tondu-Lebrun's familiarity with politics and power play between Powers-that-be (England, German Empire, Prussia, France, Holland, Russia in Flanders and central Europe got him to be appointed as chief clerk of the 1st branch of the Ministry of Foreign Affairs of Dumouriez. After 10 August 1792 he became foreign minister in the Transitional Executive Council (11 August 1792) and submitted to the National Convention a political picture of Europe as of 25 September. An advocate of an immediate peace with Prussia after the
battle of Valmy, he conducted secret negotiations, and after negotiations failed, he was a supporter of the war of conquest and defended the annexation of
Belgium and the
Netherlands. On 12 November he baptized his daughter, Civilis-Victoire-Jemmapes Dumouriez, and the God father was Dumouriez. Temporarily in charge of the Ministry of War after the resignation of Servan in October, on 19 and 31 December he filed reports on projects of England against France in which he supported, however, for a peace policy, and showed the protests of Spain for Louis XVI. Chairman of the Executive Committee, after 20 January 1793, he signed the execution order of
Louis XVI. In the early months of 1793, he tried to reconnect with
Lord Grenville, to avoid a rupture with Great Britain. On 7 March he reported to the Assembly of the rupture of diplomatic relations with Spain and its imminent entry into the war. On 2 February he summoned
Semonville to justify himself in Paris and suspended his office, after suspicision of links with Louis XVI from the publication of a letter from
Antoine Omer Talon, found in late November 1792.
Arrest and execution Denounced by the end of 1792 by
The Mountain for his close links with the
Girondins, suspected of complicity with General
Charles François Dumouriez, he was arrested on 2 June 1793 with 29 members and fellow Girondin,
Étienne Clavière. First held temporarily in office, he was brought with Claviere before the Revolutionary Court on 5 September but managed to escape on the 9th and went into clandestinity while remaining in Paris, where he hid under a variety of names during several months; while under the name of Pierre Brasseur, citizen of Liege, he was arrested on 2 Nivose year II (22 December 1793), by
Francois Heron, Agent of the Committee of General Security. Brought before the revolutionary tribunal, he was sentenced to death on 7 Nivose (27 December) under a variety of contrived and undocumented treason against the unity of the Republic, conspiracy on account of foreign powers charges, the most obvious reason being of having been called to office by Roland, Brissot, Dumouriez, all guillotined or escaped from France. He was guillotined the following day. A barely sketched attempt at defense and justification, written by him (this document does not exceed mere introductory terms in the rather pompous style of those days), was published in the year IV under the title:
Historical Memory and supporting my ministry. ==Note==