Roman Ballistae in Modern Popular Culture

[jvrjenivs]

Pardon the stupid question, but could I ask what the "win" is with a ballista?

I mean, I can understand the field pieces of the gunpowder age - how they can reduce fortifications and kill a number of men with each shot.

I'm sure it must have been effective or it wouldn't have been used - but how? What does a ballista bolt do on an ancient battlefield that a man-carried bow or crossbow does not?

Well, first of all, apart from bolt-shooters you also have pieces shooting stones (and big stones). These can be put to good use during a siege. Furthermore, a scorpio can far overshoot a bow both in range and power.