I know this is a stupid question but humor me - how do you heal your troops up after a battle? Mine keep dying from going into the next battle already wounded.

Hi, I ran into the same problem : ) After building a sanctuary when you click your hero you get by pressing R or the button Perform Ritual. That pops up a new window with a button option Chalice of Life - this will heal your troops. Only bummer is that it burns crystals so early on it is expensive.

Troops regenerate 10%/ turn on their own.
More - in garrison or with healer. (Any unit with healing ability. Even hero with Staff of Healer)
Even if you play with evil army, having healer worth little penalty to morale.
For example, with barbarians: 3 barbarians + healer then another healer, then barbarians. (As slots unlock)

Besides "Chalice of Life", there's at least one other ritual that does healing. (I think it's called "Healing Light" or something like that -- it heals all troops including guards, improves growth rates, and improves population morale. I believe it eats even more crystal than "Chalice of Life", but can be useful if you recently used "Chalice of Life" and don't want to wait for CoL to recharge.)

In addition to healing out-of-battle, you can use various tactics during battle to alleviate the issue:

At the end of battle, once you've got it "in the bag", if your hero has a heal spell use it on any unit with lots of damage (often a unit that is too slow/busy to get back to a healer). Getting your stack all of the way healed (or nearly there) will take as long as the one unit that takes longest to heal. Also, if you have healers with you, have hurt units that aren't needed to finish the job retreat and get healed. The pure archer hero I used in my last game had 3 healers and 3 horse archers. The horse archers run into battle to assist the higher tier units (partially as distraction), and they are fast enough that they can easily run back and get healed, and often rejoin the fight the turn after that. It's not unusual for all 3 healers to have something to heal every single turn once things get going (at least when up against other ranged units).

Also at the end of the battle, you can purposely drag it out to get more heal-time. If the opponent only has slow units left with no ranged ability (and that is in part up to you -- make sure you kill the slow melee unit *last* -- and take the battle to them if practical), then your entire army can fall back and you can have several turns for your healers to top off everyone's health. [Even keeping a slow/weak enemy ranged unit alive is often good for this -- especially if you leave only one unit with high defense in enemy range -- pull your other units back, heal them with your healers for as many turns as it takes, then have your hero cast one last heal on that one unit of yours to top off its health if necessary, then use the unit to kill the enemy.]

At the beginning of a battle you can place your healers close enough to any hurt units so you can get a heal off before the units run into battle. That lets you enter a battle without having to first wait for all of your units to have full health.

Another strategy I've used is that if I have one or two very hurt units and can't heal them, I may throw them in a garrison and buy replacements. Then every time a unit gets hurt just swap it out with one that's been healing in the garrison. I've only used this strategy for tier 1 troops which have fairly low upkeep. It helps keep the hero busy and lets the troops continue to level up rather than getting killed.

In addition to the above suggestions, you can also have the army sitting in a province with an infirmary building. I believe that adds an extra 10% healing per turn (effectively doubling the rate). You can still have the army explore the province, visit locations etc.