Parting shot

Rico's friend Kelley, also a history junkie, forwards this:

Spent part of the afternoon watching military historical snippets on YouTube. one of them detailed the invasion of Iran (then called Parthia) by the Roman consul Crassus. The richest man in Rome, he raised seven legions and marched into the desert. The Parthians let him do so. When he was seriously extended, they struck. The Romans formed defensive squares. The Parthians, being a horse culture, circled them, shooting arrows. Using compound bows, half the archers fired high into the air, the other half low at chest height. No matter how you held you shield, you were vulnerable. Worn down, seven Roman legions disappeared into the desert.
One of the things they learned at great cost was that the horsemen were accurate no matter which direction they were riding. If they were withdrawing, they could turn in the saddle and fire behind them (painting) to cut down their pursuers. This was called The Parthian Shot. In modern parlance, it has come down to us as 'the parting shot'.