By the time the Continental Congress approved the text of the Declaration of Independence on July 4, 1776, the 13 American colonies and Great Britain had already been at war for more than a year. A copy of the Declaration was sent by John Hancock on behalf of Congress to George Washington, the commander of the Continental Army, with instructions that it be read to the troops. Washington readily complied, hoping that the Declaration’s words would inspire “every officer and soldier … to act with Fidelity and Courage.” He hoped as well that openly proclaiming that the colonies were now “free and independent states,” no longer subject to the British Crown, would attract more recruits to join the fight “for the Defense of the Liberties and Independence of the United States.”

But it wasn’t only Great Britain with which the Americans were at war. They were at war with each other, too.

The American Revolution, not the bloody conflict between North and South in the 1860s, was the nation’s first civil war. The decision by the colonies to break away from England and its empire was by no means a unanimous one. “Somewhere between 20 and 30 percent of the population retained their loyalty to the crown,” notes the Library of Congress, while committed Patriots — those in favor of independence — accounted for about 40 percent. (As in nearly every conflict, a sizable fraction in the middle preferred not to take sides and just wanted to be left alone.)

By some estimates, there were as many as 100,000 active Loyalists in the United States during the Revolution. Many of them readily enlisted to fight on England’s side. According to “Tories,” Thomas B. Allen’s 2010 history of the Americans who fought alongside the British during the Revolutionary War, Loyalists took part in more than 500 military encounters between the battles of Lexington and Concord in 1775 and the final skirmishes in 1782. Their allegiance to the king was not mere contrarianism. They deeply opposed the Patriot cause and were no less willing than Washington’s troops or the signers of the Declaration to risk their lives, their fortunes, and their sacred honor in defense of their beliefs.

Many became refugees. When the military occupation of Boston ended in March 1776 with the evacuation of the British forces, some 1,100 Boston Loyalists and their families were forced to go with them. Abigail Adams, watching from her farm at the foot of Penn’s Hill, witnessed the departure of what she called the “largest fleet ever seen in America.” The ships carried away much of the population of Boston’s North End, permanently changing the character of what had been a keenly Loyalist neighborhood. Many of the American dissenters fled to Nova Scotia or the West Indies; others sailed, unwillingly, to England. Few ever saw their homes again.

This Fourth of July arrives amid an atmosphere of bitter political and ideological turmoil in the United States. From deep within their respective echo chambers, left-wing and right-wing Americans, egged on by shameless politicians, shallow celebrities, and media demagogues, hurl invective at anyone who doesn’t share their priorities or vote the way they do. Not for the first time in our history, countless Americans have abandoned any effort to disagree without being disagreeable, to debate those with an opposing worldview rather than demonize them.

Perhaps it is ahistorical thinking to expect anything else in a nation as big and diverse and opinionated as this one. Perhaps America will manage, as it has managed in the past, to get through the current storms without foundering and to recover the optimism and tolerance that are indispensable to decent self-government.

But on this Independence Day, it would not hurt us to remember how much sorrow and suffering can result from a refusal to countenance other points of view.

That first civil war shattered families whose members could not see eye to eye on the question of independence. Benjamin Franklin dearly loved his only son, William, who in 1762 was appointed royal governor of New Jersey largely through his father’s influence. But with the advent of the Revolution in 1775, the son remained loyal to the king. That was a decision his father deemed unforgivable.

When the Continental Congress declared William “a virulent enemy to the people of this country,” he was seized by Patriot militiamen and locked in solitary confinement. “I suffer so much in being buried alive, having no one to speak to day or night … that I should deem it a favor to be immediately taken out and shot,” William wrote. His father refused to intervene. Eventually, like so many other Loyalists, William was forced to leave his homeland for England. When the war ended, he pleaded with his father for reconciliation. But Benjamin Franklin was unbending.

The pitiless fracturing of the Franklin family was anything but unique. Throughout the colonies, Loyalists and Patriots who had been fellow citizens, friends, and family clashed. Americans loyal to Britain engaged in spying, propaganda, and local insurrections to undermine the Patriot efforts. Congress retaliated. Thousands of Loyalists were denied basic rights. Many were disarmed and arrested, stripped of their property, or sentenced to forced labor. Some Loyalists were kidnapped and held as hostages. Others were ordered to take an oath of loyalty to the Patriot cause; those who refused were expelled from their jobs. Even worse, Acts of Banishment passed by Patriot legislators forced thousands of Loyalists to flee.

All told, between 60,000 and 80,000 Americans who supported the king were driven from the country. Most were never compensated for their losses and never permitted to return. Many ended their days in poverty. Yet there was no end of Loyalists who never ceased to think of themselves as Americans. “I would rather die in a little country farmhouse in New England,” wrote Thomas Hutchinson, a Boston native who became governor of Massachusetts but was forced to spend his last years in exile, “than in the best nobleman’s seat in Old England.”

In the end, of course, the Patriots secured their independence. America grew into the world’s foremost superpower, one that still strives, however imperfectly, to be a land of the free. But we ought not to forget that part of the price of American sovereignty was the loss of innumerable men and women who were thrown out of their country because their politics differed from their neighbors’.

America’s first and second civil wars were terrible. Are we heading for a third? Or can we still find a way to pull back from the brink? “Crown thy good with brotherhood,” implores the most beloved of American hymns. It isn’t too late to make it happen. Yet.