I'd sure like to see a thread listing all of the upgrades possible with the officers patent. Early in the game it's hard to know which units you can upgrade without buying a bunch and seeing if you have enough to make them into something different.

If there's not an upgrade thread yet, maybe we should start one?

Things I know:

Thorn Warriors --> Royal Thorns. You need 50 thorns for one royal thorn
Priests --> Inquisitors or Witch Hunters. I didn't write down the exchanges.
Swordsman --> Guardsman. I haven't done this in a while but I think it was 2 for 1.

As you can see, my memory isn't very good, hence the need for a good writeup. :)

Griffin -> Royal Griffin

The ratio is purely based on leadership.

So if upgraded troop B requires 500 leadership, but original troop A requires 100 leadership, then the ratio is 5:1.

Supposedly guardsman turn into paladins too.

So how would this work for Guardsmen to Paladins then? Paladins are 220 leadership, while Guardsmen are only 50 leadership. The least common multiple of those two numbers is 1100. So to upgrade Guardsmen to Paladins, you would need to buy 22 Guardsmen to get 5 Paladins, all at once?

Or just 5 guardsmen to make one paladin. I never tried that early on, but I would assume it would happily round down for you. :)

So for the least amount of leadership 'waste', 22 guardsmen would be the better option.

Has anybody managed to make Orc Trackers or Dwarf Engineers? I've been saving up for training higher level uints AND training units of another race in hopes that I can make these. But since I have no idea what is allowed to upgrade, I am making a gamble. I'm hoping I can upgrade orcs to orc trackers and maybe dwarfs or veteran dwarfs to Engineers.

From battle_akademy.lua:
Peasant > Footman/Bowman/Priest/Pirate/Robber
Footman > Guardman/Witch-Hunter
Guardman > Knight/Horseman/Paladin
Priest > Inquisitor/Witch-Hunter
Archmage > Necromancer/Demonologist/Rune-Mage
Pirate > Sea-Dog/Ghost-Pirate
Dwarf > Cannoneer/Foreman
Orc > Veteran-Orc/Orc-Tracker
Veteran-Orc > Ogre/Ogre-Chieftain/Troll

I've also found this from the script:
I think it can be translated to simple English like this:
NewUnit_Number = Round-down ( OldUnit_Leadership * OldUnit_Count / NewUnit_Leadership )

Priest's Leadership = 50/each
Inquisitor's Leadership = 100/each
You have 20 Priests.
When upgrading to Inquisitor, you'll get 50 * 20 / 100 = 10 Inquisitors.

Footman's Leadership = 35/each
Guardman's Leadership = 50/each
You have 25 Footman.
When upgrading to Guardman, you'll get 35 * 25 / 50 = 17.5 = 17 Guardmen.

Thanks. Now at least if you don't find the units you like, you have more possibilities to get them (since their predecessor is almost sure to come out)

There is a new questgiver, named Arian, who, after completing certain easy quest, will change people into demons. You need Officer's Patent for this, and trophies. He's different than usual conversions, because he converts in ratio 1:1. For example, 5 Runemages into 5 Archdemons, 40 Demonologists into 40 Executioners, or 40 Paladins into 40 Executioners or 20 Witchhunters into 20 Demons. That way you can get more leadership worth of troop than you had before (with executioners even much more) or less (as with Archdemons).

Now the only thing needed is a better description of how this work in-game.

Seriously Kataury needs to put a little more effort so we don't have to do threads for things like this. (Or is there an in-game description I'm not aware of?)

Great, where can he be found?

Thanks for the info - I myself have run out of Swordsman to turn into Guardsman, so I'll be using the Peasant-Sworsman-Guardsman route. :)

Neat that you can turn Archmages into Demonologists, or Griffins into Royal Griffins, those units were usually very scarce.

The Demon idea is a great one for an early all-Demon army. I wish Lizardmen were also available earlier on, at least the Level 1-3 units. It wasn't until Shattera (Shetarra?) that I have first seen them in my first Walkthrough.