Effectiveness of assault troops

When I first saw the assault troops I was like, THESE GUYS ARE SO AWESOME!!!!!
But when I did get them, I started to lose gold a lot from having to heal them, since they normally just die so quickly.

However, when my assault troops started to level up, I realized a few things about them.
 
   1. Never have more than 25% of your army as assault.
   2. Do not be tempted by their unbreakable proc since it can be completely useless a lot of the time (especially to dwarves and I think undead? Sorry guys I'm a dwarf).
   3. DO NOT EVER EXPOSE THEM TO ARCHERS!!!!!!!!!

Rule number 3 is the golden rule about them.

Pros/Cons

Pros
  Has incredibly increased damage by level 3 and above.
  Is unbreakable, but this can lead to being overconfident.
  Has increased strength compared to LI
  Has increased movement (not sure if this is exclusive to only dwarves or not)
Cons
  Has no armour to start with.
  Cannot equip armour.
  You have to manually call the retreat.
  Loses their effectiveness when flanked even on just one side.
  Can easily be considered dead if separated from the group

Tactics
 
  Assault troops are designed to be effective flankers, and are almost necessary for armies with slow movers. Assault troops are basically beserker units as I like to call them since they do nothing but die and attempt to kill as many as they can before they die. But we don't want all of them to die right?
  In one pvp match that I can remember in tier 3. I was fighting against a better armed and better levelled enemy and he even had HI while I only had 1 assault and 4 LI. However his army composition is poor having 2 assaults and 1 HI, his positioning was in such a way in which the assaults would be the ones tanking the damage, not the HI. I used this to my advantage by killing of his 2 assaults, which wasn't hard at all, then surrounding his 'barely scratched' HI with all 5 units on all 4 sides. This prevented him from escaping and from doing any real damage due to the -35 melee due to rearing and flanking. He could've won if only he had at least 1 other LI unit and if he had positioned his troops better.
  For you to be successful in your battles you need a good army composition which compliments the abilities of another unit, but there are army compositions that hinder this. Examples of bad army compositions would include:
  -2 archers 2 assault (your assault will die easily enough on its own, and you decide to kill it even more with friendly fire?)
  -1 HI/LI 1<assault (Do you really want to use your assaults to tank the damage?)
  -Artillery 5 assault (NEVER DO THIS!)
  -1 of everything! (diversity is not always the answer when you are at war)
I can go on forever, but you get the point; hopefully.
  Remember that HI are not always best paired with an overkill amount of archers, for me, the fact that archers have friendly fire made me turn down the option of being and elf, and even including archers in my tactics (no offence to you elven folks out there, but it's true). Even though HI have really strong armour, they can still be killed by friendly fire. So why not replace the archers with assault as a substitution to the damage dealer of your troops? If you time your engagements correctly the AI behind every unit will only target your HI and only your HI alone, use this to your advantage by throwing your assaults in there to chop up the enemies trying to kill your beloved HI in their futile attempts. The advantage here is that the assault AI knows who swing his axe/knife/hammer/sword/(bony hands?) at. However make sure that if you use this tactic, there are no archers that are crazy distances away from you. Archers forced right at the front, just so they can shoot are fine, since they will be forced to melee in a matter of seconds. Another thing here is that you don't have to worry an awful lot about you HI being reared or flanked, because you assault units will rear all those who make a futile attempt to kill your HI with rearing and flanking. This tactic is also applicable to LI. I have tried this tactic with LI and I strongly believe that It will work even better with HI due to their role being the ones who tank the damage. But remember that you should have more HI or LI than assault in your army and that it will be your LI or HI that the enemy focuses down first. One more thing, if for some miraculous reason, that the enemy kills one of your 'tank units' the ones who were attacking the tank unit that just died have a higher possibility of attacking your assaults rather than the other tank units.
  Another thing that you can use assault units for is killing all the archers. while your tank units enter combat. For this though, your assault units need to swift with taking out the archer units, and make sure you demoralized them bad, because an archer running back after retreating can be really devastating if not paid attention to quickly enough. After you have wrecked havoc among their ranks of archers, you can now rear which is the fun part! After that just watch as your army rips your enemy to shreds since their beloved archers have deserted them. If ever the enemy archers have guards, make life hard for their frontal troops behind terrain to force him to send out his guard, afterwards, let your assault units enjoy their party with dem' archers.

  Anyways, this is only based on my opinion and slightly small experince in BC but this is my first guide, sorry for the messy layout, I'm not that good of a writer. Please do give constructive criticisms (if you have any). Stay safe.