In February of the following year General Lafayette, who had distinguished himself as a volunteer in the rebel army, returning to France on leave, brought a commission from the American congress to Dr Franklin as sole plenipotentiary of the United States to the court of France. From this time until the close of the war it was Franklin's paramount duty to encourage the French Government to supply the colonists with money. How successfully he discharged this duty may be inferred from the following statement of the advances made by France upon his solicitation:—In 1777, 2,000,000 francs; in 1778, 3,000,000 francs; in 1779, 1,000,000 francs; in 1780, 4,000,000 francs; in 1781, 10,000,000 francs; in 1782, 6,000,000 francs; in all, 26,000,000 francs. To obtain these aids at a time when France was not only at war, but practically bankrupt, and in defiance of the strenuous resistance of Necker, the minister of finance, was an achievement, the credit of which, there is the best reason for believing, was mainly due to the matchless diplomacy of Franklin. Writing to the French minister in Philadelphia, December 4, 1780, the Count de Vergennes said—

"As to Dr Franklin, his conduct leaves congress nothing to desire. It is as zealous and patriotic as it is wise and circumspect, and you may affirm with assurance, on all occasions where you think proper, that the method he pursues is much more efficacious than it would be if he were to assume a tone of importunity in multiplying his demands, and above all in supporting them by menaces (an allusion to the indiscreet conduct of Franklin's colleagues), to which we should give neither credence nor value, and which would only tend to render him personally disagreeable."

Again, February 15, 1781, Vergennes wrote:—

"If you are questioned respecting an opinion of Dr Franklin, you may without hesitation say that we esteem him as much on account of the patriotism as the wisdom of his conduct; and it has been owing in a great part to this cause, and the confidence we put in the veracity of Dr Franklin, that we have determined to relieve the pecuniary embarrassments in which he has been placed by congress. It may be judged from this fact, which is of a personal nature, if that minister's conduct has been injurious to the interests of his country, or if any other would have had the same advantages."

Franklin had been for some years a martyr to the gout, which, with other infirmities incident to his advanced age of seventy-five, determined him to ask congress, in 1781, to relieve him, in a letter so full of dignity and feeling, that no one can read it even now, after the lapse of nearly a century, without emotion.

"I must now," he wrote, after disposing of official topics, "beg leave to say something relating to myself—a subject with which I have not often troubled congress. I have passed my seventy-fifth year, and I find that the long and severe fit of the gout which I had the last winter had shaken me exceedingly, and I am yet far from having recovered the bodily strength I before enjoyed. I do not know that my mental faculties are impaired,—perhaps I shall be the last to discover that,—but I am sensible of great diminution of my activity, a quality I think particularly necessary in your minister at this court. I am afraid, therefore, that your affairs may some time or other suffer by my deficiency. I find also that the business is too heavy for me and too confining. The constant attendance at home, which is necessary for receiving and accepting your bills of exchange (a matter foreign to my ministerial functions), to answer letters, and perform other parts of my employment, pre vents my taking the air and exercise which my annual journeys formerly used to afford me, and which contributed much to the preservation of my health. There are many other little personal attentions which the infirmities of age render necessary to an old man's comfort, even in some degree to the continuance of his existence, and with which business often interferes.

"I have been engaged in public affairs, and enjoyed public confidence in some shape or other during the long term of fifty years, and honour sufficient to satisfy any reasonable ambition; and I have no other left but that of repose, which I hope the congress will grant me by sending some person to supply my place. At the same time I beg they may be assured that it is not any the least doubt of their success in the glorious cause, nor any disgust received in their service, that induces me to decline it, but purely and simply the reasons I have mentioned. And as I cannot at present undergo the fatigues of a sea voyage (the last having been almost too much for me), and would not again expose myself to the hazard of capture and imprisonment in this time of war, I propose to remain here at least till the peace—perhaps it may be for the remainder of my life—and if any knowledge or experience I have acquired here may be thought of use to my successor, I shall freely communicate it and assist him with any influence I may be supposed to have, or counsel that may be desired of me."

Congress not only declined to receive his resignation, but with its refusal sent him a commission, jointly with John Adams and John Jay, who had been the agent of the congress in Spain, to negotiate a peace. Cornwallis had surrendered at Yorktown on the 17th of October of that year, the anniversary of Burgoyne's disastrous surrender at Saratoga just four years before, and a farther prosecution of the war beyond what might be necessary to secure the most favourable terms of peace was no longer advocated by any party in England. Active negotiations with Franklin and his associates were opened, and on the 30th of November a preliminary treaty was signed by the English and American commissioners; a definitive treaty was signed on the 30th of September 1783, and ratified by congress January 14, 1784, and by the English Government on the 9th of April following. At the conclusion of the preliminary treaty Franklin renewed his application to congress to be relieved, to which he received no answer. A few weeks after signing the definitive treaty, he renewed it again, but it was not until the 7th of March 1785 that congress adopted the resolution which permitted "The Honourable Benjamin Franklin to return to America as soon as convenient," and three days later it appointed Thomas Jefferson to succeed him.

During his stay in Paris Franklin gave by no means all his time to political problems. He wrote a paper for the Royal Society on the subject of balloons, a topic which, under the auspices of the Montgolfiers, attracted a great deal of attention at that time in France. Sir Joseph Banks commended it for its completeness. To some one who asked the use of the new invention Franklin replied by asking, "What is the use of a new-born baby?" In 1784 he was appointed by the French Academy one of a commission ordered by the king to investigate the phenomena of "mesmerism"; and to a large extent he directed the investigation which resulted in the disgrace and flight of Mesmer and his final disappearance from the public eye. Franklin's Information to those who would Remove to America, his New Treatise on Privateering, his Essay on Raising the Wages in Europe by the American Revolution, his Letter to Vaughan on Luxury, his Story of the Whistle, together with his private as well as official correspondence, kept the world constantly talking about him and wondering at the inexhaustible variety and unconventional novelty of his resources. "You replace Dr Franklin," I hear, said the Count de Vergennes to Jefferson when they first met. "I succeed, no one can replace him," was Jefferson's reply.