Hoplite armour exhibit at the Corfu Museum (Photo credit: Wikipedia)
The Greeks were all about fitness, and if they were in battle, they couldn’t show off their abs while wearing metal cuirass’. And yes, despite what they show in the movie ‘300’, all the hoplites and Greek warriors that could afford armour, wore it. Anyway, where was I.. Oh, yes, abs. So the Greeks still wanted to show off to the enemy without getting killed, so they got an idea, why not decorate the cuirass with the abs? So that’s what they did, though armour decorated like this is very expensive, so it was usually only the commanders who were able to have one. One use that it is possibe the “abs” on the armour had, (other than showing off, of course) is that the ridges could deflect spear thrusts, because if the spear is going head on against the flat face of the armour, there is a good chance it is going to pierce, whereas hitting at an angle, or the slope of a ridge, there is nothing to catch onto, and so the spear is deflected.
The breastplates were made by forging red-hot bronze until the desired shape, thickness and size is reached. Because it was just so expensive to buy copper and tin, and then alloy them, and THEN go through the laborious work to forge it into armoure that would resist breaking or being pierced in battle, the eventual buyer will have to pay quite a lot for it. But then, when trade began to progress, Greece was right in the middle of the shipping routes, and so they got much of the world’s commerce, meaning more money, meaning more bronze, meaning more armour. This meant that more people were willing to join the army, because the better equipment they had, the less chance of getting killed and the higher chance of being put in one of the better units, meaning more pay. So with trade, the military power of Greece increased.