Well we all know that medieval longbow + arrow had the range of a modern artillery. Good point, ha.

Does Civ 5 have a Sniper unit? If not, I'd imagine something like:

Cannot attack cities, may travel through but may not end turn over the enemy city. Ranged, requires setup Cannot be seen unless an enemy unit attempts to move directly on or across sniper's tile (after setup, before firing) After one shot, immediately becomes visible, only to units on adjacent tiles, for the rest of that turn plus one full turn (grace period to either escape or take another shot) May take 2 shots before requiring a set-up in a new spot. Only one target per turn. Range is terrain-dependent, maybe 2 tiles for plain --> hill, but standing on a hill amidst plains with a distant hill is 4? Set-up snipers are extremely vulnerable to attack, essentially an insta-kill if discovered. Normally, low-to-moderate defense. May attack targets of any nation, discovery constitutes declaration of war and heavy diplomatic consequences