In a letter to Mr. David Hartley, dated February 2, 1780, Franklin showed something of the feelings of the Americans with respect to the English at that time:—

You may have heard that accounts upon oath have been taken in America, by order of Congress, of the British barbarities committed there. It is expected of me to make a school-book of them, and to have thirty-five prints designed here by good artists, and engraved, each expressing one or more of the horrid facts, in order to impress the minds of children and posterity with a deep sense of your bloody and insatiable malice and wickedness. Every kindness I hear of done by an Englishman to an American prisoner makes me resolve not to proceed in the work.

While at Passy, Franklin addressed to the Journal of Paris a paper on an economical project for diminishing the cost of light. The proposal was to utilize the sunlight instead of candles, and thereby save to the city of Paris the sum of 96,075,000 livres per annum. His reputation in Paris is shown by the following quotation from a contemporary writer:—

I do not often speak of Mr. Franklin, because the gazettes tell you enough of him. However, I will say to you that our Parisians are no more sensible in their attentions to him than they were towards Voltaire, of whom they have not spoken since the day following his death. Mr. Franklin is besieged, followed, admired, adored, wherever he shows himself, with a fury, a fanaticism, capable no doubt of flattering him and of doing him honour, but which at the same time proves that we shall never be reasonable, and that the virtues and better qualities of our nation will always be balanced by a levity, an inconsequence, and an enthusiasm too excessive to be durable.

Franklin always advocated free trade, even in time of war. He was of opinion that the merchant, the agriculturist, and the fisherman were benefactors to mankind. He condemned privateering in every form, and endeavoured to bring about an agreement between all the civilized powers against the fitting out of privateers. He held that no merchantmen should be interfered with unless carrying war material. He greatly lamented the horrors of the war, but preferred anything to a dishonourable peace. To Priestley he wrote:—

Perhaps as you grow older you may ... repent of having murdered in mephitic air so many honest, harmless mice, and wish that, to prevent mischief, you had used boys and girls instead of them. In what light we are viewed by superior beings may be gathered from a piece of late West India news, which possibly has not yet reached you. A young angel of distinction, being sent down to this world on some business for the first time, had an old courier-spirit assigned him as a guide. They arrived over the seas of Martinico, in the middle of the long day of obstinate fight between the fleets of Rodney and De Grasse. When, through the clouds of smoke, he saw the fire of the guns, the decks covered with mangled limbs and bodies dead or dying; the ships sinking, burning, or blown into the air; and the quantity of pain, misery, and destruction the crews yet alive were thus with so much eagerness dealing round to one another,—he turned angrily to his guide, and said, 'You blundering blockhead, you are ignorant of your business; you undertook to conduct me to the earth, and you have brought me into hell!' 'No, sir,' says the guide, 'I have made no mistake; this is really the earth, and these are men. Devils never treat one another in this cruel manner; they have more sense and more of what men (vainly) call humanity.'

Franklin maintained that it would be far cheaper for a nation to extend its possessions by purchase from other nations than to pay the cost of war for the sake of conquest.

Two British armies, under General Burgoyne and Lord Cornwallis, having been wholly taken prisoners during the war, at last, after two years' negotiations, a definitive treaty of peace was signed on September 3, 1782, between Great Britain and the United States, Franklin being one of the Commissioners for the latter, and Mr. Hartley for the former. On the same day a treaty of peace between Great Britain and France was signed at Versailles. The United States Treaty was ratified by the king on April 9, and therewith terminated the seven years' War of Independence. Franklin celebrated the surrender of the armies of Burgoyne and Cornwallis by a medal, on which the infant Hercules appears strangling two serpents.

When peace was at length realized, a scheme was proposed for an hereditary knighthood of the order of Cincinnatus, to be bestowed upon the American officers who had distinguished themselves in the war. Franklin condemned the hereditary principle. He pointed out that, in the ninth generation, the "young noble" would be only "one five hundred and twelfth part of the present knight," 1022 men and women being counted among his ancestors, reckoning only from the foundation of the knighthood. "Posterity will have much reason to boast of the noble blood of the then existing set of Chevaliers of Cincinnatus."

On May 2, 1785, Franklin received from Congress permission to return to America. He was then in his eightieth year. On July 12 he left Passy for Havre, whence he crossed to Southampton, and there saw for the last time his old friend, the Bishop of St. Asaph, and his family. He reached his home in Philadelphia early in September, and the day after his arrival he received a congratulatory address from the Assembly of Pennsylvania. In the following month he was elected President of the State, and was twice re-elected to the same office, it being contrary to the constitution for any president to be elected for more than three years in succession.