To finally break the archers and knights meta.
Nearby Militia-line units gain plus 1 pierce armor for every 5 Militia units, to a max of 4 pierce armor when 20 are grouped together. Be like the Georgians’ Monaspa but pierce armor instead for the Militia-line. Research cost: 75 food, and 50 gold. It’s a separate technology from supplies. Is the tech too cheap? Should it be changed in some way? Lower the pierce armor bonus?
What if 10 militia gain plus 1 pierce armor, and 20 militia gain plus 2 pierce armor? Could more civs gain Shield Wall with this change?
Should it be every 7 Militia? So you will need 28 Militia to gain plus 4 pierce armor? 7 plus 1, 14 plus 2, 21 plus 3, 28 plus 4. As the Militia take casualties in battle, they will lose the extra pierce armor as the Shield Wall becomes weaker.
How strong would this make militia vs archers? Note, not every civ gets Shield Wall, this tech is available in the feudal age. This will allow all in Man At Arms to a degree. It will allow for more aggressive infantry pushes. Since the extra pierce armor will make them stronger vs towers and town centers as well.
Even in the Imperial Age this will allow the militia-line to be quite aggressive against defences and tanky vs archers. The following civs get Shield Wall. Celts (faster Militia) Vikings(Militia more HP/chieftans) Bulgarians (Free Militia upgrades/Bagains) Teutons (Militia extra melee armor). Franks and Britons, no special bonus.
I think giving this tech to some civs would make it too strong. But some others, not so much. There might need to be some balance changes to counter the new stronger militia.