In January 1778, what would be immortalized as the rag-tag Continental Army was at its raggiest and taggiest. The brutal winter at Valley Forge scared off many of the soldiers it hadn’t killed or broken.

Mocked as “the Ragged Lousey Naked Regiment,” the 1st Rhode Island Regiment wasn’t recruiting many new troops. Because desperation often spawns disruption, the Rhode Island Assembly on Feb. 14, 1778, welcomed “every able-bodied negro, mulatto, or Indian man slave in this state to enlist”—offering freedom to those still enslaved. One hundred black soldiers enlisted before June, when slaveowners helped repeal the law.

Yes, there was slavery in Rhode Island, which was a center of American slave-trading. With large farms conducive to the plantation system, Rhode Island had the highest percentage of slaves—and blacks—in the post-Declaration of Independence North. That presence—which hovered between 6 and 11 percent of the total population—led to the opportunities and backlash of 1778.

After another 40 black people nevertheless enlisted, the 140 black men of 225 soldiers helped the 1st Rhode Island Regiment, make history. Today, visitors to Bloody Run Brook off Rhode Island Route 114 see a plaque honoring the site “where the First Black Militia fought… in the Battle of Rhode Island.” The Americans had massed near Newport, hoping to break through a formidable British military line. Just over 10,000 American troops faced 7,000 better-armed, better-trained British troops, including Hessians. Ultimately, the Americans failed to break the British, but the 1st Regiment did its work honorably. They were defending the western side of the hill where the American troops had gathered. Three times, British and Hessian mercenaries tried to break through that line on Aug. 28, 1778—assuming these mostly black troops would be easily overrun. In resisting so effectively, again and again the soldiers of the 1st Rhode Island Regiment established a reputation as formidable fighters. The Hessian commander said he feared if he ordered another attack, his men would attack him.

Of course, much of the Revolutionary War was a war of attrition; the Americans’ most important accomplishment was surviving—and outlasting the British. The heart of the war shifted south, so the troops subsequently saw little action. In early 1781, now reconstituted as the Rhode Island Regiment, our heroes patrolled the “Neutral Zone” in the Hudson River Valley, where brigands raided repeatedly, shifting allegiances depending on their prey.

Tragically, on May 14, 1781, marauding Loyalist “cowboys” raided the troops’ temporary headquarters on the Croton River in Westchester, New York. Targeting the white commander Colonel Christopher Greene, the raiders killed his black bodyguards, who fought fiercely to defend him. One account reports “his body was found in the woods, about a mile distant from his tent, cut, and mangled in the most shocking way.”

That special fury tells the real story of freedom springing forth. A white commander of black troops was particularly threatening. True, British soldiers were making their own contribution to freedom for blacks, recruiting so many slaves especially in the South that the historian Gary Nash credits Great Britain with fomenting “the greatest slave rebellion in American history.” But the sight of former slaves fighting alongside their former enslavers for freedom, respected the kind of seductive subversion that eventually freed the slaves.

It’s fitting on July 4 weekend to ponder not only what freedoms we have but how those freedoms took hold. Most Brits were what we would later call Darwinians, trusting freedom to evolve naturally, organically, peacefully. And indeed, much of British democratic history isn’t about a Patrick Henry facing a binary choice—liberty or give me death—but individual and collective circles of freedom expanding. Slavery was gradually snuffed out, as blacks acquired equal rights in England without dramatic revolutions.

Not so in America, where progress was dramatic, erratic, often violent. When I was in college, even our Earth science classes had us embracing Stephen Jay Gould’s swashbuckling, disruptive theory of punctuated equilibrium—learning that we became human in occasional bursts followed by long periods of settling in—not Darwin’s imperceptible adjustments. And indeed, we tell our history through great moments and great people, through giant steps not baby steps.

With this in mind, American revolutionists would want the Rhodes Island Black Regiment to have acted more dramatically, to have left more of a legacy—but they didn’t. And British evolutionists could try taking heart in the small steps forward during the Revolution: Ultimately, 5,000 black troops did fight during the Revolution, the First Rhode Island Regiment troops fought so impressively and bravely that only one-third of them survived. Alas, the sinister spread of slavery in the South suggests that freedom for hundreds of thousands of persecuted black slaves was neither leaping ahead dramatically nor progressing slowly.

Consider, however what happened. George Washington originally opposed recruiting slaves, fearing arming them for a slave rebellion. He relented in desperation, recruiting and freeing them, which normalized and humanized them. Consider the moving memories of “Doctor Harris,” a veteran of the First Rhode Island Regiment, addressing an anti-Slavery society in 1842. “My nearest blood, except that which runs in my veins, was shed for liberty. My older brother was shot dead instantly in the Revolution. Liberty is dear to my heart. I cannot endure the thought, that my countrymen should be slaves.”

And consider the most famous painting from the War—and possibly from American history: Washington Crossing the Delaware. Sitting by Washington’s knee is a black man. His presence is so notable a whole legend grew up falsely claiming that soldier was Prince Whipple, one of Washington’s bodyguards. Clearly, this was an imaginative rendition: Had Washington been standing like that, the story would have been about Washington Drowning in the Delaware. Still, that presence further normalized and romanticized blacks and black participation in America’s patriotic journey, precisely when the fight over slavery was intensifying.

Both noble and normal actions by the oppressed unsettle the oppressor creating cognitive dissonance. A Hessian officer in 1777 reported: “the Negro can take the field instead of his master; and therefore no regiment is seen in which there are not Negroes in abundance, and among them are able-bodied, strong and brave fellows.” The French officer François-Jean Marquis de Chastellux called the three-quarters black 1st Rhode Island Regiment “the most neatly dressed, the best under arms, and the most precise in its maneuvers.” No wonder, George Washington eventually, belatedly, freed his slaves; Thomas Jefferson agonized over slavery; and James Madison stewed, admitting during the revolution, that freeing slaves “would certainly be more consonant with the principles of liberty which ought never to be lost sight of in a contest for liberty.”

The Revolutionary War historian Bernard Bailyn called this the spillover effect. In his classic book The Ideological Origins of the American Revolution, Bailyn showed that ideas spread, sometimes dramatically, sometimes steadily, creeping their way into hearts, worming their way into minds. Ultimately, the results were, dare we say it, revolutionary.

Of course, having a conducive atmosphere for such change is essential. The Revolution wouldn’t have had a spillover effect for freedom without creating an ideological and institutional infrastructure for freedom as well. So, on July 4, let’s celebrate the gradual bubbling up, and the dramatic, wonderfully subversive spillover, well aware that just as it grows slowly, freedom can die slowly too.