Vauban [0] designed his first handbook for trench warfare after the Siege of Maastricht in 1673. Prior to that, siege mining and sapping had been used by Rome and Warring States China since about the 4th century BCE. This also marked the first purported use of poison gas in warfare, when the tunnels were intentionally filled with smoke.

[0] https://en.wikipedia.org/wiki/S%C3%A9bastien_Le_Prestre_de_V...