When George Washington arrived in Philadelphia in 1787 to attend the Constitutional Convention, his first ceremonial visit was to the newly expanded home of Benjamin Franklin. In his joint biography of the men he calls “the two most celebrated heroes” and “the two indispensable authors of American independence,” historian Edward J. Larson speculates that Washington walked rather than rode in his carriage from the house where he was staying, because riding would have entailed bringing his enslaved coachman and groom into the courtyard of the man who had months earlier become president of the Society for Promoting the Abolition of Slavery.

As America’s founding shows, leadership requires collaboration. Franklin and Washington were the two founders best at forging teams. Franklin wrote an autobiography around the theme of how to win friends and influence people, and Washington won a revolution by doing so. They each made more friends than rivals, unlike Hamilton and Jefferson and Adams.

Larson laudably tries to counter the tendency of historians, especially biographers, to focus on individuals rather than teams. There have, of course, been many notable exceptions, such as Doris Kearns Goodwin’s “Team of Rivals” and “The Bully Pulpit,” or Tom Chaffin’s recent “Revolutionary Brothers,” about Thomas Jefferson and the Marquis de Lafayette. In “Franklin & Washington,” Larson’s approach is to create not a buddy narrative but instead a leadership study showing how two different personalities can forge a partnership. “To explore their historic collaboration, this book traces their shared history in a dual biography that looks for overlaps and stresses connections,” he writes.

One problem that Larson faces is that Franklin and the 25-years-younger Washington had a lot of mutual respect, but they rarely spent time together. Although they used words like “respect” and “esteem” and even “veneration” when they signed their letters to each other, the contents were usually businesslike rather than intimate or personal. There is no evidence that Franklin ever deeply engaged with Washington intellectually (as he did with Joseph Priestley) or emotionally (as he did with fellow printer William Strahan). So try as he may, Larson has produced a book that is not as much a tale of teamwork and friendship but instead two well-written and interesting biographical narratives that occasionally intertwine.

There were three great projects that Franklin and Washington worked on together, or at least in parallel. The first was in forging a unified army out of a ragtag collection of state militias. The Continental Congress sent Franklin in 1775 to Cambridge, Mass., where he stayed with Washington and “produced the framework for a new Continental Army.” They had one area of disagreement: Washington insisted that his army not include any enslaved people or free blacks, even those who had been serving in the militias.

Their second great dual endeavor was one they worked on from afar, with little coordination. As envoy in France, Franklin wrote letters of recommendation for European officers seeking commissions, secured loans and other military funding, and enlisted the French navy and army in helping the colonial cause. After a while, Washington felt inundated and annoyed by all the letters of recommendation, but they did produce for him Count Pulaski, Baron von Steuben and the Marquis de Lafayette.

Their third endeavor together was serving as the two lions at the Constitutional Convention in 1787. There the main traits that they shared proved invaluable. Both believed that the fledgling nation needed to become a strong national union rather than a mere confederation of states. They were also brave enough to believe in compromise. “The business of the Convention should be conducted with moderation, candor & fairness,” Washington said, and Franklin capped the contribution with a speech in favor of the compromises made. “The older I grow,” he said (he was 81), “the more apt I am to doubt my own judgment, and to pay more respect to the judgment of others.” They transcended, in what should be a model for today, partisan bitterness and rage. As one member said of Franklin, “His presence and advice, like oil on troubled waters, have composed the contending waves of faction.”

Great leadership teams generally are not composed of people with matching personalities. Instead, they are forged by people who bring different strengths and traits to the table. America’s founding needed people who were brilliant, such as Jefferson and James Madison, and those who were passionate, such as John Adams and Samuel Adams. Likewise, as Larson shows, Franklin and Washington brought two different sets of traits.

Washington was aloof and revered. He embodied the noble virtues of duty, courage, honor, fidelity and discipline. With his aristocratic bearing, he seemed to be made of marble and standing on a pedestal. At one point during the convention, a reward was offered if a member would have the temerity to pat Washington on the shoulder. Gouverneur Morris took the wager and got such a cold stare that he later said, “Nothing could induce me to repeat it.”

While Washington was the beneficiary of inherited and married wealth, Franklin was a self-made tradesman who proudly portrayed himself as a “middling” or middle-class man of humble origin. His virtues were not the noble ones but the practical ones he listed in his autobiography, such as industry, frugality, humility and moderation. Into his 80s, he was boyish, playful, approachable, sly, humorous and earthy, with a wink in his eye, relishing a common touch and eschewing all pretenses of nobility,

Their greatest difference was on slavery, and Larson confronts that issue with unflinching directness. As a young man, Franklin owned two or three household slaves, and he had allowed the advertising of slave sales in his newspaper. But as he reached middle age he saw his error, let his slaves wander off, became a supporter of black education, wrote essays decrying the effect of slavery on society and eventually became president of Pennsylvania’s abolition society.

Washington not only retained 300 enslaved people, he was known for his harshness. He clothed and housed them poorly, had them whipped regularly, and pursued them vigorously when any tried to escape. While at the Constitutional Convention, he knew that Pennsylvania law would liberate those who were in the state more than six months, so he secretly rotated them in shifts back to Mount Vernon. “I wish to have it accomplished under pretext that may deceive both them and the Public,” he wrote to his secretary. His chef Hercules figured out the scheme, protested that he was loyal and was given an exemption by Washington to stay in Philadelphia with him. When he got the chance, he fled. Washington later signed the nation’s first fugitive slave law.

Larson is also tough on Washington’s protege Madison on this issue. When Franklin submitted a petition calling on Congress to “step to the very verge of the powers vested in you, for discouraging every Species of Traffick in the Persons of our fellow Men,” Madison made sure that the petition was quietly sent without debate to a committee where it would be killed. “The now inflexible stance of Madison on slavery and the Constitution put him, and Washington, on a collision course with Franklin,” Larson writes.

Franklin’s last published piece of writing was a scathing but funny satire, parodying a speech by a Georgia congressman, that purported to be an address given in the Congress of Algiers justifying slavery of Europeans using the same rationales. Because of the slavery issue, his relationship with Washington ended on a chilly note. When Franklin died, Jefferson proposed that administration members should wear black badges for a month. President Washington quashed the proposal.

“No one can know what might have happened had the two icons of the revolution, Franklin and Washington, stood together against slavery at the nation’s founding,” Larson writes. “As it happened, they split over the issue and with them the nation.” Partly their differences were regional, the merchant and shopkeeping economy of Philadelphia vs. the plantation economy of Virginia. But they were also based, as Larson shows, on personality and values. Washington’s embodiment of noble virtues and aristocratic grandeur made him a revered commander and an iconic leader, but Franklin showed that on slavery, an outlook based on simple virtues and humility can be more clear-eyed.

Franklin & Washington

The Founding Partnership

By Edward J. Larson

Morrow. 335 pp. $29.99