I have been reading up a bit on the Roman Legions and have a couple questions.
First of all why was the gladuis replaced by the spatha? The spatha was a fair bit longer than the gladius and therefore significantly harder to wield in close formation. Following the myriad successes achieved with the gladius why change?
Secondly, does anyone know the reason for switching to, and then away from, the lorica segmentata? Was it more effective? Easier/harder to make and maintain?
Thirdly, why was the rectangular scutum replaced with the more oval shields of the later legions?
Finally how many of these changes were made due to the changing role of the legions from a offensive juggernaut to a defensive immovable object?