@Boris Gudenuf : thanks a lot, great post, I'm going to update the spreadsheet, but I have a few questions/suggestions about the changes.
The Jager, better fitted in Elite Melee or Recon/Skirmisher ?
Although the 'Jaeger' started in Germany in the Renaissance (1498 CE, first rifled firearms, Augsburg, Germany), they were a tiny proportion of any military force - first regular unit was a single company raised in 1631, so their use as 'skirmishers' was always pretty rare on the ground. In contrast, the term came to be used for Elite Infantry extensively in both the Russian and German/Prussian Armies from the time of the Napoleonic Wars and throughout the 19th century - precisely the time that you start needing an 'elite' designation for infantry.
Because yes, Elite Melee has a missing link after the Grenadier
Warrior -> Bronze Warrior -> Swordsman -> Man-at-Arms -> Musketman -> Grenadier (flintlock musket) -> Jager (rifle) ? -> Marine -> Modern (Mechanized) Marine
Suggested Elite Melee Line:
Warrior -> Heroic Warrior -> Swordsman -> Man-at-Arms -> Musketman -> Grenadier -> Jager -> Assault Infantry -> Mechanized Infantry
Heroic Warrior, because the men with all the Bronze tended to be the Aristocratic warriors out in front - see Homer's 'Illiad' which pretty accurately captures the spirit of the Bronze Age 'Hero'
'
Assault Infantry is a direct translation of the German
Sturmtruppen or
Stosstruppen, the End-Of-WWI infantry that figured out how to break the trench stalemate. The Allies used terms like Assault Party or Assault Company - but the word 'Assault' is the key, they are the tactical descendants of the Grenadiers of the black powder years.
Mechanized Infantry, which starts appearing in WWII, were the ones that accompanied the tanks, and so got involved in the Main Attacks. They also tended to be much more heavily armed: the German Panzer Grenadier company had twice the number of machine-guns as a regular infantry unit, and its own light infantry artillery that in the regular units was at Regimental level. The American Armored Infantry had a bazooka and a vehicle-mounted .50 caliber machine-gun for each Squad, where the regular infantry had a bazooka team in each platoon at best, and nothing heavier than a rifle-caliber machine-gun.
But we have the same issuer with Recon/Skirmisher (modified):
Slinger -> Peltast (javelin) -> Skirmisher (bows) ? -> Crossbowman -> Explorer (musket) -> Ranger (flintlock musket) -> Jager (rifle) ? -> Commando -> Special Forces
Suggested Recon/Skirmisher Line:
Slinger -> Psiloi (javelin) -> Peltast (javelins/spear/sword) -> Huntsman (Bow/Longbow) -> Forester (musket) -> Ranger (flintlock musket) -> Scout (rifle) -> Commando -> Special Forces
Psiloi, as long as we're using Classical Greek Terminology, were the very light infantry with javelins and a small 'target' shield. They could also have self-bows or slings, but the primary point was that they had no melee weapons at all, and relied on speed and dispersion to avoid the enemy.
Peltast was the heavier version, with a large wooden/hide shield, and a sword or spear to supplement his javelins. He was much more likely to get into a close fight if he had to, but didn't wear body armor, so was generally faster and lighter than the 'core' infantry. Roman Velites were actually a form of Peltast.
Huntsman - the only kind of 'scout' in the European Middle Ages were men who made their living sneaking through the woods hunting game or finding it for the aristocrats, occasionally scooped up and sent out to hunt human Game. Usually armed with a bow or even a longbow, but primarily interested in Finding and Reporting rather than Finding and Fighting.
Forester - the Renaissance 'Scout', could even include (very slow firing) rifles as in the German unit I mentioned above.
Scout - the foot infantry units of the 20th century (Modern-Atomic Eras) all had men designated as Scouts, sometimes right down to the company level (US Army, WWII). They were armed just like regular infantry, but frequently had more training in 'sneak and peek' tactics and frequently included snipers to do a little harassing of the enemy as well as reconnaissance.
Seems that I will have trouble to mix mounted units with Recon/Skirmisher line (because of the way the upgrade mechanism is designed with the equipment), so I'll move them to the light cavalry (and give the whole line the ability to move after attack), something like that, not using war horses, but requiring more advanced spears than the base spearman (to prevent rider to be available before mounted skirmisher), so what about this :
Chariot (javelin) -> Mounted Skirmisher (bows) -> Rider (iron spears) -> Horseman (iron spears + light armor) -> Lancer -> Dragoon -> Cavalry -> Armored Cavalry (early armored car) -> Armored Cavalry (WWII light tank) -> Armored Cavalry (modern armored car)
Suggested Light Cavalry Line:
Chariot (javelins) -> Mounted Scout (javelins, bows) -> Rider (metal-tipped javelins/spears) -> Horseman (metal spears, javelins, shields, light armor) -> Dragoon -> Lancer -> Cavalry -> Armored Cavalry (armored cars) -> Armored Cavalry (light tanks) -> Armored Cavalry (modern multi-wheeled armored cars)
Mounted Scout more accurately indicates the use of the first 'horse-riders': loose formation, keep their distance, a mix of relatively close-range missile weapons
Horseman - difference between him and his predecessor is that he carries a shield and possibly some body armor, and is much less worried about getting into contact with the enemy.
Dragoon - the first 'Lancers' were almost as heavily-armored as Knights, so really don't belong in the Light Cavalry line. On the other hand, Dragoons, mounted infantry on really cheap, small horses, were used extensively throughout the Renaissance and into the 18th century as scouts, raiders, and skirmishing cavalry.
Lancer - here is the 'light cavalry' of the early Industrial Era, without armor and using the lance to 'supplement' the charge of heavy cavalry and to drive off enemy light cavalry.
The "conscript" line would look like that:
Light Spearman (wooden spears) -> Spearman (iron/bronze spears) -> Heavy Spearman (iron/bronze spears + heavy shields) -> Pikeman -> Tercio -> Fusilier -> Rifleman -> (Mechanized) Infantry -> Modern (Mechanized) Infantry
Mechanized Infantry does not belong in the conscript line, because nobody has ever been able to afford to put all their infantry into mechanized vehicles unless they kept their army very, very small. The last two entries, reflecting the infantry of the 20th century, would be: Infantry (rifles, machine-guns) -> Infantry (automatic weapons, rocket-launchers, mortars)
I'm not sure that we need to represent the supply line for the (commonly used) light shields in any line BTW, but I propose to base the "light spearman"/"spearman" difference on the type of spear instead of light/medium shield. It could be based on using light armor (or not) if that make more sense ?
Actually, could be appropriately based on Type of Shield/Armor. The earliest spearmen and Bronze Age spearman particularly all seem to have shields made of wicker (Mesopotamia) or Hide/Leather stretched over a wooden frame (Europe, Greece, Egypt). By comparison, the spearman/Hoplites/Triarii of the Classical Era carried heavy shields made primarily of wood with metal facing or reinforcements, and wore at least metal helmets and canvas/leather body armor, sometimes body armor of metal covering them head to knee.
Note that this also changes the 'Source' for the unit's equipment from animal (hides, bone) to mineral/timber (metal, wood) increasing the differentiation between them.