Military mining, undermining or tunnel warfare is a siege method based on mining techniques which has been used since antiquity against a walled city, fortress, castle or other strongly held and fortified military position. A counter mine is a mine dug to allow defenders to attack miners, or destroy a mine threatening their fortifications.
The Greek historian Polybius, in his Histories, gives a graphic account of mining and counter mining at the Roman siege of Ambracia:
The Aetolians countered the Roman mine with smoke; according to Polybius, this was the first time poison gas was used.
Another extraordinary usage of siege-mining in the ancient Greece, where during Philip V of Macedon's siege of the little town of Prinassos, according to Polybius, "the ground around the town were extremely rocky and hard, making any siege-mining virtually impossible. However, Philip ordered his soldiers during the cover of night collect earth from elsewhere and throw it all down at the fake tunnel's entrance, making it look like the Macedonians were almost finished completing the tunnels. Eventually, when Philip V announced that large parts of the town-walls were undermined, the citizens surrendered without delay."