Polybius (2.33) reports that the
Gauls at the
Battle of Telamon (224 BC) had inferior iron swords which bent at the first stroke and had to be straightened with the foot against the ground.
Plutarch, in his life of
Marcus Furius Camillus, likewise reports on the inferiority of Gaulish iron, making the same claim that their swords bent easily. These reports have puzzled some historians, since by that time the Celts had a centuries long tradition of iron workmanship.
[2] In 1906 a scholar suggested that the Greek observers misunderstood ritual acts of sword-bending, which may have served to "decommission" the weapon.
[3] Such bent swords have been found among deposits of objects presumably dedicated for sacred purposes. The speculation has been repeated since.
[2] Radomir Pleiner, however, argues that "the metallographic evidence shows that Polybius was right up to a point. To judge from the swords examined in this survey, only one third could be described as conforming to the quality which he ascribed generally to Celtic swords. Even so, it is quite possible that even some of the better quality swords would have failed in battle."
[3] Nevertheless he argues that the classical sources are exaggerated. Plutarch's claim that Celtic swords would bend completely back is implausible, as only a slight bending would be likely.
[3] Pleiner also notes that metallurgical analysis performed on Celtic swords suggests that they were only
work hardened and only very few were
quench hardened, even though they frequently contain enough carbon to be hardened (in particular the swords made from
Noric steel). Quench hardening takes the full advantage of the potential hardness of the steel, but leaves it brittle, prone to breaking. Quite probably this is because
tempering wasn't known. Tempering is heating the steel after quenching at a lower temperature to remove the brittleness, while keeping most of the hardness.