When workers came upon historic ordnance buried at Fort McHenry last week, there was every reason to stop work and take precaution.

The British navy famously rained bombs and rockets on the fort in September 1814. Some artillery shells from the day were packed with gunpowder. Old ammo still turns up from time to time around Fort McHenry National Monument and Historic Shrine.

The Baltimore Police bomb squad arrived. Then came a crew of bomb techs from Joint Base Andrews. Authorities turned off the nearby gas lines. They warned neighbors to brace themselves for a bang.

In the end, there was no explosion. The ordnance was determined to be inert — a fully corroded cannonball, so there was no threat, 1st Lt. Noelle Grey, a spokesperson for Joint Base Andrews, said this week.

Crews carefully removed the cannonball and carried it away. It will be trashed, Grey said.

The relic was found within the park grounds just south of the main road. Officials did not have any photos of it.

“Because Fort McHenry served as a military installation for more than a century, these types of discoveries are not uncommon, and park rangers and law enforcement partners are trained to respond quickly and safely,” said park ranger Shannon McLucas, a spokesperson for the fort.

Still, it’s uncertain whether the artifact was actually a British bomb from the War of 1812. That’s when some 1,000 defenders withstood the bombardment, forcing the British ships to withdraw and inspiring “The Star-Spangled Banner.”

Authorities haven’t said whether they know much at all about the relic’s origins.

Fort McHenry remained an active military installation and was used as a prison camp later for captured Confederate soldiers and sympathizers. Civil War cannonballs are found more often and still potentially explosive.

In 2008, crews were dumping dredged materials from the Baltimore Harbor on Hart-Miller Island when they discovered a 25-pound cannonball in the mud.

That cannonball was suspected to be from the Civil War and was still explosive with black powder inside, a member of the State Fire Marshal’s office told The Baltimore Sun.

In the months prior, crews dredging the Patapsco River near Fort McHenry found three 8-inch cannonballs, The Sun also reported.