Excavations have found evidence that the fortifications had collapsed or had been “deliberately felled” before about 140, when the site was bombarded by Roman sling bullets, arrows, and artillery missiles.

Hundreds of sling bullets made of lead have been found; these would have been unsuitable for training because they cannot be seen in flight, and they would have been more expensive than alternatives of stone or clay.

[13] The strategic context is briefly mentioned, in a part of the Historia Augusta generally held to be reliable, and recently-excavated details have allowed reconstructions of many aspects of the assault and Roman victory.

[14] After the death of the Emperor Hadrian, Antoninus Pius rose to the throne and moved quickly to expand the empire beyond the limits put in place by his predecessor.

Lollius Urbicus, a native of Tiddis in modern Algeria, had been one of a few senior officers selected by Hadrian to put down the Bar Kokhba revolt, which had been crushed with colossal loss of life and suffering.

The Selgovae, in the regions of present-day Kirkcudbrightshire and Dumfriesshire immediately northwest of Hadrian's Wall, were among the first of the Caledonian tribes to face Lollius Urbicus's legions together with the Otadini.

[24][25] This is compatible with a carefully-prepared barrage of a variety of missiles, possibly intended to suppress enemy resistance while Roman soldiers advanced up the hill to melee combat.