How long would it take for medieval sappers (let's say 1300 AD) to undermine a castle wall? About how many yards per day could they advance in the absence of opposition? - Quora
Medieval warfare artwork hi-res stock photography and images - Alamy
Carved Cross – Sapped Of Strength, Left To Wither And Fade Away (2019, Vinyl) - Discogs
Fighting Under the Earth: The History of Tunneling in Warfare - Foreign Policy Research Institute
Strategy - Medieval strategy | Britannica
File:Military and religious life in the Middle Ages and at the period of the Renaissance (1870) (14598281410).jpg - Wikimedia Commons