Slitherine

Ok, the mission were you have to defeat Pyrrus, third mission with elephants. I have mostly heavy infantry (2x hastati, 2x Principes, 1x triarii) 2x velites, 1x Elephants, 1x Militia, and 1x Nobles (the militia is NOT my starter, I sold everything and bought a noble first).

It is the map with a river through the middle, so put everything on long hold, militia in the river, my elephants + skirmishers lined up against my enemy's. My cavalry and general are on the far left on a slow advance. The enemy has a line of spearmen, of varying levels, and a second line of cavalry, skirmishers and 2 elephants. The skirmishers are every other one, with the elephants on the far right.

Now I had two suprises. 1) The enemy archers can fire accross the entire map. Fine, I got no problem there, my troops are very elite anyway, and all have decent shot armour. Then a volley hits my cavalry. One dies. That one man who dies is my legate

I didn't even know that was POSSIBLE! I think I might try getting a group of archers + advanced marksman to go general hunting

It's a fluke, bad luck, whatever but I've had it happen twice now to me. If you put your Legate by himself and charge skirmishers they won't fire on him so apparently the AI can't specifically target your Legate.

Hmm... i didn't know that. I will have to watch out, then.

Ive had my legate die to a volley once- multiplayer game, too. Luckily, my units were already nearly in contact, and his legate died literally seconds later

In the manual, it says hill is good for archers as they shoot down from it.
So, in shooting down, archers and javelin throwers get somekind of bonus as their missiles go down to the hearts of earth?

And, elephants seems to get killed before their Health points get used up. Maybe this is something of critical hits by enemy melee combat units.
As elephants have many HPs, something like 250 or more, depending on how high its level, so they can sustain multiple hits, and it means many trial
if hit is critical or not.

Every shot has a slim chance of doing critical damage, killing the target. Ranged fire seems to affect other enemy units that are in the target area, but don't seem to affect your won troops. In this case, I suspect that the target was your cavalry, and your Legate happened to get hit with one of the stray shots, which randomly became a critcal hit. Scratch one Legate. I regularly decimate incoming elephants with archers. The regular damage isn't all that effective against such healthy targets, but the occasional critical makes it worthwhile, especially if you've trained your archers in "Weakspot Targeting" or similar.

Hills give the ranged weapons a little bonus, to represent the assist from gravity.

Yes, i you notice, there are little yellow arrows often floating up from your soldiers under arrow fire. This represents critical hits, just like the golden horseshoes. I believe the calculation is a possibility of hitting, then a chance of critical damage (as opposed to normal damage) and then a chance of the target dodging the critical damage (based on shot armour).