A few weeks after the Declaration of Independence was adopted, Franklin received a long letter from Dubourg addressed to "My Dear Master," which justified at least the inference that Vergennes leaned towards the cause of the Colonies. Encouraged by this letter, Congress elected three envoys to represent America in France: Benjamin Franklin, Thomas Jefferson and Silas Deane. Deane was already in France. Jefferson was compelled by the ill health of his wife to decline, and Arthur Lee, then in London, was elected in his stead.

After a voyage of thirty days in the Reprisal, commanded by Captain Wickes, a small war-vessel in the service of Congress, Franklin reached Quiberon Bay. Thence he proceeded by land to Nantes and from Nantes to Paris. After his arrival at Paris, he lodged at the Hôtel d'Hambourg, in the Rue de l'Université, until he found a home in the house at Passy placed at his disposal by M. Donatien LeRay de Chaumont. For a time, he courted retirement, but, as France was drawn more and more closely into concert with the American rebels, his activity became more and more open, until the surrender of Burgoyne at Saratoga induced that country to abandon the policy of connivance and secret assistance, which it had pursued behind the screen, supplied by the commercial adventures of Caron de Beaumarchais, even before Franklin landed in Europe, and to enter into the treaty of alliance with the United States which made Adams, Lee and himself our fully acknowledged representatives at the French Court. The circumstances, under which the news of Burgoyne's capitulation was communicated to Franklin and his colleagues, constitute one of the most thrilling moments in history. The messenger, who conveyed it, was Jonathan Loring Austin, a young New Englander, and the Secretary of the Massachusetts Board of War; and he was sent in a swift vessel for the very purpose by the State of Massachusetts. "Whatever in thy wise providence thou seest best to do with the young man, we beseech thee most fervently, at all events, to preserve the packet," is the tactless petition that Dr. Cooper is said to have addressed to Heaven on the Sunday before Austin sailed. The rumor of his coming preceded his arrival at Passy, and, when his chaise was heard in the court of the Hôtel de Chaumont, Deane, Arthur and William Lee, Ralph Izard, Dr. Bancroft, Beaumarchais and Franklin went out to meet him. "Sir," said Franklin, "is Philadelphia taken?" "Yes, sir," replied Austin. At this Franklin clasped his hands and turned as if to go back into the house. "But, sir," said Austin, "I have greater news than that. General Burgoyne and his whole army are prisoners of war!" The night of American adversity was now for the first time lit up by a real augury of dawn, and the treaties of amity and commerce and alliance between France and the United States, in the existing state of French feeling, followed almost as a matter of course.

When, weak from his long voyage, Franklin started out on the journey from the seashore to Paris, which led him at one point through the forest haunts of a bloodthirsty gang of robbers, he was seventy years of age. "Yet," he could truly declare some ten years later to George Whatley, "had I gone at seventy, it would have cut off twelve of the most active years of my life, employed too in matters of the greatest importance." These were indeed years of precious service to his country and of a fame for himself as resplendent as any in modern history which lacks the lustre of military glory. What Washington was to America in the field, Franklin was to her in the foreign relations upon which it may well be doubted whether the success of her arms did not at times depend. To obtain material aid in the form of money and munitions of war, soldiers and fleets from the one powerful country in Europe, which manifested a disposition to side actively with America, was the cardinal object of American policy after the outbreak of the Revolution, and rarely has any man ever been more richly qualified for the accomplishment of any object than was Franklin for the accomplishment of this. In the first place, his liberal and sympathetic nature, with its unrivalled capacity for assimilating foreign usages and habits of thought and feeling, slid without the slightest friction into every recess of its French environment. This was a fact of supreme importance in the case of a people so distinctive in point of race and temperament, and so irredeemably wedded to their own national prepossessions and prejudices as the French. Doubtless, Franklin was too wise a man not to have courted French favor, in a social sense, to some extent as a matter of political policy. Then, too, there is every reason to know that he was sincerely grateful to France for the benefits which she showered upon his country and himself. But it was mainly the spell of La Belle France herself, with her cordial appeal to his delight in existence, which finally produced the state of mutual affection that enabled him to say with truth that he loved the French and that they loved him. What this meant to our cause we can easily divine when we remember how wholly some of the colleagues of Franklin failed to recommend themselves to the good will of the people, whose good will it was of the utmost concern to America that they should conciliate, or to abstain from untimely dissensions. The exact reverse of what Franklin said of himself might be said of them. They disliked the French People, and the French People disliked them.[29] More than once it required all the management of Franklin to placate feelings that they had aroused in Vergennes, the French Minister, by lack of tact or good judgment. On one occasion, after being lectured by Adams, on the subject of the American paper money, held by citizens of France, Vergennes wrote to Franklin that nothing could be less analogous than the language of Adams to the alliance subsisting between his Majesty and the United States. In the same letter, he asked Franklin to lay the whole correspondence between Adams and himself before Congress, adding that his Majesty flattered himself that that Assembly, inspired with principles different from those which Mr. Adams had discovered, would convince his Majesty that they knew how to prize those marks of favor which the King had constantly shown to the United States. No choice was left to Franklin except to comply with the request and to do what he could to satisfy Vergennes that the sentiments of Congress and of Americans generally were very different from those of Adams. But unfortunately, before the correspondence between Adams and Vergennes could reach Congress, Adams had again, by his officious conduct in another particular, elicited a sharp rebuke from Vergennes. This correspondence, too, Vergennes requested Franklin to lay before Congress, which Franklin did with comments not more severe than the occasion called for, but which the pride of Adams, already deeply infected with the jealousy of Franklin, which he shared with Arthur Lee, so far as his manlier and wholesomer nature allowed, never fully forgave. "He," Vergennes said of Adams, in a letter to La Luzerne, "possesses a rigidity, a pedantry, an arrogance and a vanity which render him unfit to treat political questions."

After peace was restored between Great Britain and the United States, the strictures of Adams upon Vergennes and France became so imprudent and outspoken that Franklin wrote to Robert Morris:

I hope the ravings of a certain mischievous madman here against France and its ministers, which I hear of every day, will not be regarded in America, so as to diminish in the least the happy union that has hitherto subsisted between the two nations, and which is indeed the solid foundation of our present importance in Europe.

Four months later, Franklin, to use his own words, hazarded a mortal enmity by making this communication to Robert R. Livingston:

I ought not, however, to conceal from you, that one of my Colleagues is of a very different Opinion from me in these Matters. He thinks the French Minister one of the greatest Enemies of our Country, that he would have straitned our Boundaries, to prevent the Growth of our People; contracted our Fishery, to obstruct the Increase of our Seamen; and retained the Royalists among us, to keep us divided; that he privately opposes all our Negociations with foreign Courts, and afforded us, during the War, the Assistance we receiv'd, only to keep it alive, that we might be so much the more weaken'd by it; that to think of Gratitude to France is the greatest of Follies, and that to be influenc'd by it would ruin us. He makes no Secret of his having these Opinions, expresses them publicly, sometimes in presence of English Ministers, and speaks of hundreds of Instances which he could produce in Proof of them.

All this Franklin believed to be

as imaginary as I know his Fancies to be, that Count de V. and myself are continually plotting against him, and employing the News-Writers of Europe to depreciate his Character, &c. But as Shakespear says, "Trifles light as Air, &c." I am persuaded, however, that he means well for his Country, is always an honest Man, often a wise one, but sometimes, and in some things, absolutely out of his senses.

A clever and just flash of characterization but for the usual inability of Franklin to refer abnormal conduct to anything short of dementia.[30] In the latter part of the same year, Franklin again had occasion to write to Robert Morris,