Dictionary of National Biography, 1885-1900/Galgacus
GALGACUS, or (according to the best readings) CALGACUS (fl. circa A.D. 84), Caledonian chieftain, held the command of the native tribes when Agricola, the Roman governor of Britain, invaded Caledonia in his last campaign. Agricola found him encamped near Mons Graupius (Tacitus, Agric. xxix.; so in the editions of Wex, Kritz, and Orelli, 2nd edit.; Church and Brodribb read 'Grampius;' Skene, Celt. Scotl. i. 52, 'Granpius'), and a great battle ensued in which the Romans were victorious. The scene of this engagement has been variously identified with Dealgan Ross near Comrie, Ardoch, Fife, and Urie in Kincardineshire. Skene (Celt. Scotl. i. 54) supposes that previous to the battle the Romans occupied the peninsula formed by the junction of the Isla with the Tay, being protected by the rampart of the Cleaven Dyke, and that Galgacus was encamped at Buzzard Dykes. The date of the battle is usually given as A.D. 84. (Skene, 'A.D. 86;' on the chronological difficulty, see Celt. Scotl. i. 51 note; Merivale, Hist. of the Romans, vii. 329). Before the fight Galgacus is represented by Tacitus (Agric. xxx-xxxii.) as delivering an harangue, denouncing the Roman plunderers of the world. ('Raptores orbis . . . ubi solitudinem faciunt, pacem appellant,' &c.) His personal fortunes in the battle are not stated, nor is his name subsequently mentioned. Tacitus speaks of him as 'inter plures duces virtute et genere præstans.'
[Tacitus, Agricola, xxix-xxxii. &c.; Skene's Celtic Scotland, i. 52-6.]