Armor Upgrades - Can someone explain how they work?

[Camcolit]

As title, I rarely play factions or use troops that benefit from them so didn't really bother looking into it. I read some old threads with some conflicting information. I guess what I'm looking for is -

How many upgrades/reforms are there and when do they come in? Right now my Galatian troops seem to have one armor upgrade level at 380ish turns.

How much of an upgrade is it? On the unit card it seems to indicate one point of additional armor but in other threads I have heard it is 2.5, then in another on the M2TW base game someone said it varies depending on armor type.

Who benefits, is it just for Celtic/Germanic? troops? Seems odd that nobody else would get them.

If anyone has reliable info on this it would be much appreciated. Thanks!

[Shoebopp]

There are currently 5 armor upgrades, each one triggered by certain events

1 - Thorakitai Reforms
2 - Barcid Reforms
3 - Panoply Reforms
4 - Marian Reforms
5 - Celtic Twilight

Each number corresponds to a value for the key armour_ug_levels in export_descr_units.txt. For example, for Galatian Retainers, it has

0, 1, 5

for their armor upgrade levels. This means they, like every other unit in the game, start with 0 armor upgrade levels, which doesn't correspond to any events. However, the Galatian Retainers then gain an armor upgrade level at the 1st event and the 5th event, which correspond to the Thorakitai Reform and the Celtic Twilight. That explains why your Galatian troops have a single armor upgrade - the Thorakitai Reforms have triggered, and your Galatians will gain another in the Celtic Twilight Reforms which may occur in about 60 or so turns.

Each armor upgrade level increases the armor by 1. You can see it by setting up a custom battle with variably armor-upgraded units. Every faction benefits from the armor upgrade when recruiting new units. Existing units though need to be retrained to enjoy the armor upgrade.

There's also a curious game engine limitation where triggering any of the events will also enable the armor upgrades before it in the numbering scheme. For example, if the Barcid Reforms trigger before the Thorakitai Reforms, which is highly likely for a Qart-Hadasht player, then the armor upgrade for the Thorakitai Reforms will also be activated. Then, if there exists a unit with armour_ug_levels of 0, 1, 2 (there doesn't exist a unit like this in the game), it will have both the 1st event's armor upgrade and the 2nd one applied. Thus, the unit would have +2 armor.

Fun fact: the Numidian Nobles have armour_ug_levels of 0, 2, 3. This means you can field Numidian Nobles with +2 armor by turn 328 if you've triggered the Barcid Reforms and waited for the subsequent Panoply Reforms. This transforms them from a slightly superior skirmishing unit to a melee cavalry unit capable of standing toe-to-toe with Celtic Noble Cavalry

[Camcolit]

Thanks a lot for that, finally makes some sense!