Zosimus, New History 3.21
Zosimus (Greek Ζώσιμος): Early Byzantine, pagan author of a history of the Roman Empire, published in the first quarter of the sixth century CE.
The translation of Zosimus' New History offered here was printed in 1814 by W. Green and T. Chaplin in London, and was probably prepared by J. Davis of the Military Chronicle and Military Classics Office. The translator is anonymous. The text was found at Tertullian.org. The notes were added by Jona Lendering.
[3.21.1] They who were besieged in the castle kept off the enemy with darts of all kinds, and because they had no stones within, they made balls of pitch which they set on fire and flung at the besiegers; nor was it difficult to hit those they aimed at, as they threw from above, at a great multitude collected together.
[3.21.2] The Roman soldiers, however, omitted no kind of warlike policy, but retained their usual courage. They threw and shot at the enemy great stones and darts, out of engines as well as bows, and those were contrived to strike several persons at one throw.
[3.21.3] The castle being situated on a hill, and fortified with two walls, sixteen large towers, and surrounded by a deep ditch, which in one part was introduced into the castle to furnish its inhabitants with water, the emperor ordered his soldiers to collect earth enough to fill up the ditch, and raise on it a mount to the height of one of the towers.
[3.21.4] He likewise resolved to make a mine under the wall, beyond the inner precinct, for the purpose of surprising the enemy. The enemy obstructed there who were raising the mount by continually casting darts upon them; the emperor, therefore, himself invented means of defence against the darts and fire-balls. He left the care of the mine and raising the mount to Nevitta and Dagalaiphus.
[3.21.5] Then giving to Victor the command of a detachment of horse and foot, he ordered him to reconnoitre the whole country between that place and Ctesiphon; and if any enemy should appear with the design of attempting to divert the emperor from the siege, to frustrate any such attempt; and likewise by bridges and other improvements to render the road from thence to Ctesiphon more easy for the march of the army.