Some 1,800 years ago, Roman troops used "whistling" sling bullets as a "terror weapon" against their barbarian foes, according to archaeologists who found the cast lead bullets at a site in Scotland.

The bullets were found recently at Burnswark Hill in southwestern Scotland, where a massive Roman attack against native defenders in a hilltop fort took place in the second century A.D. See Photos of Roman Battle Site and Sling Bullets

These holes converted the bullets into a "terror weapon," said archaeologist John Reid of the Trimontium Trust, a Scottish historical society directing the first major archaeological investigation in 50 years of the Burnswark Hill site.

"We think they're for close-quarter skirmishing, for getting quite close to the enemy."

Sling bullets and stones are a common find at Roman army battle sites in Europe.

Sling weapon secrets

Whistling sling bullets haven't been found at any other Roman sites, but ceramic sling bullets with holes punched out have been discovered at battle sites in Greece from the second and third centuries B.C, Reid said.

Deadly in expert hands

At the time of the Roman attack on Burnswark Hill, slings were used mainly by specialized units of auxiliary troops "auxilia" recruited to fight alongside the Roman legions.

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