Encyclopedia of historical weapons - Gladius
The Legions patterned their short swords after those of the Spanish Celts. The historian, Polybius, says they were introduced into the army during the second Punic War. The Gladius of Caesar's time until Tiberius had a slight curve in the edge of the blade. The Fulham type and the Pompeii type had edges which were completely parallel. This sword was intended as a thrusting weapon. This was the best way to use a sword in tight formation. Using the sword in a slashing motion would cause the soldier to open his side to attack. The Gladius was replaced by the traditional long swords of the barbarians in the late empire.