Autograph letter by Pierre-Joseph-Marie Proudhon, signed and dated 7 November 1862. 3 pages in black ink on a bifolium. Fold of the bifolium weakened, without affecting the text. Not included in the correspondence published by Lacroix in 1875.
Significant and likely unpublished letter from Proudhon to his publisher Alphonse Lebègue, whom he considers "the cause of liberty in France and independence in Belgium" in these lines. 

Proudhon underscores the importance of his ideological struggle for federalism in Europe, following the controversial publication of his pamphlet La Fédération et l’unité en Italie, and a few months before his political testament Du Principe fédératif. He fiercely criticizes his famous adversary Adolphe Thiers’ Histoire du Consulat et de l’Empire. Since his years in Brussels, Proudhon had intended to write a book debunking the Napoleonic myth as promoted in Thiers' work.

After permanently leaving Belgium two months earlier, Proudhon was now facing reactions from the Belgians to his articles predicting the annexation of their country by Napoleon III - who would supposedly be influenced by the unification of Italy. Against centralized unification, Proudhon opposes federalism, which, according to Jorge Cagiao y Conde, is "the constructive or positive aspect of a body of work that, until the end of the 1850s, had remained in a negative or critical phase. We must therefore take Proudhon's words seriously: after the demolisher, there is indeed a builder. Proudhon's federal theory undoubtedly holds a prominent place in the history of the federal idea. Just as the United States Constitution of 1787 marks a before and after in the history of federalism, we can also consider that there is a before and after Proudhon". Determined to spread and defend his ideas, Proudhon also talks of a new pamphlet project on federalism:

"The principle of federation that I have established is gaining ground, and intelligent Belgians cannot fail to understand that their true safeguard lies there. [...]

My pamphlet has stirred as much emotion as it did in Belgium: the masses, enamoured with unity and Garibaldism, are against me. But the clear-sighted are rallying with vigour, the reaction is taking hold; already the tone of the newspapers has softened; it is becoming apparent that the matter must be re-examined—the suspicion is spreading that the cause of liberty and of the Republic is being undermined by Garibaldian unitarism. One more pamphlet from me, 30 or 40 pages at most, and my idea will triumph, I dare say, on all accounts. Within three months, Belgians will acknowledge that with this idea of federation, on which I intend to base all internal and foreign policy, the annexation of their country will become impossible. You know how quickly ideas travel in France: we are witnessing one of those turnarounds. It takes, after all, a timely and forcefully articulated contradiction, aimed at men of authority!... Suppose instead of addressing Mazzini and Garibaldi I had targeted my argument at Mr. Grauquillot or [Alphonse] Peyrat [editor of La Presse], it would have achieved nothing, I would have wasted my time and paper.

This, dear Mr. Lebègue, is confidential and between us. Take note of the information I share, if you deem it useful, but do not quote me. In a fortnight, you will receive my fourth article. L’Office, in memory of my collaboration, wishes to publish a short commentary and a few excerpts, which I believe would benefit everyone. You know I seek neither praise nor approval; only publicity, and with that, I am content. You would be the cause of liberty in France and of independence in Belgium […]"

Proudhon's letter also contains an interesting passage on the fierce rivalry between him and Adolphe Thiers. As a politician, Thiers had notably rejected outright Proudhon's well-known bill of 31 July 1848 proposing a "third-income tax" on property revenues. In retaliation, Proudhon attacks in this letter Thiers’ magnum opus as a historian, hisHistoire du Consulat et de l’Empire. It is the very structure of Thiers’ hagiographic tale of Napoleon that Proudhon calls into question here:

"I have begun reviewing this final portion of Mr. Thiers’ work: it is exceedingly weak. The author’s mistake was to publish each volume as he wrote it, and to write each one as the bookseller requested copy. The result, inevitably, was that after 25 years the writer’s talent would be worn down, and the ending would not match the beginning. He should have conducted the entire work in parallel; everything should have started simultaneously, allowing constant revision and improvement. And once the work was complete, the manuscript should have been delivered to the publisher, who would then have done what was best."

A remarkable synthesis of Proudhon’s hopes for a federal future among nations, captured in this impassioned political letter. For Sainte-Beuve, Proudhon’s correspondence must be considered an essential part of his work: “all the letters I have seen from him are serious: none are trivial”; he adds: “the history of his mind lies in his letters: that is where it must be sought” (quoted in Jean-Philippe Chaumont, Revue d’Histoire Moderne & Contemporaine, 1991, p. 649).