Well in that case the answer is it depends on what you want to accomplish. It should be possible to still fight a retreat and withdraw without any losses, but it's going to be close (esp. if they have light cav) and you will not cause much damage at all. However, if you are willing to take a few losses it should be possible, depending on the opposing setup and your numbers, to fight and win with minimal losses.

Certain units are going to be the bane of your existence. I'm just going to start typing my thoughts, so read on at your leisure.

- If you're up against archer chariots, I wouldn't bother fighting because they are just as fast as you are, can shoot like you can, and will mulch your horses if they catch you. If you're up against heavy/non-ranged chariots, it's possible to win but really tricky because they are fast, basically super horse mulching versions of light cav. When going up against chariots I firmly recommend you only fight them in city streets with massed heavy infantry, it negates the chariot's advantages, and huge blobs of heavy infantry will usually mulch chariots pretty quickly in the thin streets.

- As for elephants, depends on what kind again. The non-arrow shooting elephants shouldn't be too hard, the goal is to route them, or even better drive them mad and then hope they plow back into their own infantry lines. Be careful about this because if they catch you, you are toast. Also keep everything you have away from amok elephants, period.

- Light cav is going to be realistically your biggest problem. They're fast enough to catch you and strong enough to beat you if the catch you. Best thing is to not engage stacks with too many light cav, and if you are forced to, always make use of terrain to your advantage. Fortunately most all light cav is very vulnerable to missile fire, so if you concentrate as much fire as you can early on to these guys, you should be able to kill enough of them that they route before they even get to you, or will cause minimal damage to your lines before they route or you kill them all.

- Missile cav. Depends on what you're up against. You've got your basic HA, your Camel archers, and your javelin types. Against normal HAs, you should expect to take some losses. Depending on what units you have vs. them, you could come out better or worse for wear. If you had say for example a unit of Cataphract Horse Archers vs. some normal light unarmored Horse Archers, I'd recommend trying to pin the other HAs into a corner with your cataphracts and engage in melee, because your armored cataphracts are going to be much strong and are slower on the run. Normal HA vs normal HA, sheer weight of fire and quality of units will win the day. Always remember to try and shoot at whatever you're aiming at's rear. Camel archers are troublesome because they fighten your horses when too close. Thankfully they are slow, so again weight of fire is going to be key, just don't get too close until they are ready to or are routing.

- Foot missile infantry. Now here's a pain. 9 times out of 10 these guys can outrange your HA, so be prepared to take losses unless you can catch them running. I've found that most often the best thing you can do with these guys is to charge a few of your HA's into their rear and flanks, then hope for a quick route. Be prepared to take some decent casualties if you go up against stuff like chosen archer warbands or pharoah's bowmen. Javelin skirmisher shouldn't be a problem because you can easily outrange them and are much faster.

- Heavy cav. Be careful and you can take them on. Heavy cav should never be able to catch you, unless you are up against a fresh unit and your guys are exhausted. Keep your distance and use a unit or two to "kite" them, and another few units to keep the fire on. Even generals will fall in good order with good management and concentrated fire. The only thing I would offer, and this will come with experience, is once you kill a general in a generel's cav unit, do NOT pursue the other ones when they route. You've killed the named char, hence that unit will never come back, so best not to waste time, arrows, and possibly your guys trying to take them all out. The thing to watch out for is to ensure when they route, they're going to stay routing. I've had more than a few instances where I've killed the general and his remaining unit rallied and made my life hell.

- Normal infantry. Your lunch. These guys should be cake to beat. Just remember to keep your distance and try to shoot into their rear or unshielded side for best effect. Do NOT try to shoot into the front of a phalanx as it will be

- Artillery. Stay out of range. Thankfully the AI usually isn't smart with stuff like ballistas and the subvariants. Concentrated fire is your key if they're going to be a problem, arty crews are very vulnerable to missiles. If you're sneaky, you can often get a unit or two of HA behind the other stack's lines to cause some hell with their onagers if they have any. Usually a few barrages and then follow up with a good charge to the rear of the unit will result in a quick rout.

Combine all these and you should be able to come up with a winning recipe. Fight some custom battles to help you get a better feel. Start off with say 10 HAs of your against say 5 random non-ranged infantry units on the grassy plains with clear weather to start. Repeat until you start to get a good feel for what you are doing. Then, try something just a little bit different. Add a single unit of light cav to the infantry setup you already did and see how that changes things. Just keep doing this and you'll eventually figure out what works best for you.

Lastly, I almost forgot. Our resident Horse Archer nut and overall brilliant guy Doug-Thompson wrote an HA guide here: https://forums.totalwar.org/vb/showthread.php?t=73479 . The unit stats and whatnaught are obviously for M2TW, but the tactics and other information apply perfectly to RTW.

Best of luck!