The muse for this story is a humble piece of stone, no more than an inch square. Sometime in the mid-19th century, it had been fashioned into a gunflint—an object that, when triggered to strike a piece of steel, could spark a small explosion of black powder and propel a lead ball from the muzzle of a gun with mortal velocity.

Archaeologists often come across gunflints. That’s because during the 19th century, firearms were considered mundane items, owned by rich and poor alike. Gunflints, like shell casings now, were their disposable remnants.

But this gunflint is special.

In 2008, my students and I, working with nearby residents, unearthed this unassuming little artifact during an archaeological dig in a little Pennsylvania village known as Christiana. We found it located in what today is a nondescript corn field, where a small stone house once stood.

For a few hours in 1851, that modest residence served as a flashpoint in America’s struggle over slavery. There, an African American tenant farmer named William Parker led a skirmish that became a crucial flareup in the nation’s long-smoldering conflict over slavery.

It’s been 160 years since the uprising, which for most of its history was known as the Christiana Riot, but is now more often referred to as the Christiana Resistance, Christiana Tragedy, or Christiana Incident. In taking up arms, Parker and the small band of men and women he led proved that African Americans were willing to fight for their liberation and challenge the federal government’s position on slavery. Finding a broken and discarded flint offers a tangible piece of evidence of their struggle, evoking memories of a time when the end of slavery was still but a hope, and the guarantee of individual liberty for all people merely a dream.