The militia guide
Here's some words on an often neglected unit: militia. People tend to think of them as weak, slow, and only useful for static defense, but most of that is a myth really. When used correctly, they can be a deadly secret weapon, putting heavy pressure on the flanks of an offensive and giving you're opponent the chilling idea feeling you're "everywhere", losing provinces to ghosts. I'll tell you how in a minute, but lets take a closer look at them first.
1) extremely cheap and quick to build
3) often overlooked: GREAT upgrade features
5) manpower cost
1) extremely cheap and quick to build:
Excluding manpower for the moment, militia only consumes food and a tiny bit of goods. They're also very quick to build, you seldom need more than an L1 barracks even at the higher levels. This means that you can produce a lot of them relatively easy; and even if their individual combat stats look bad, their value for money is very good. For example, you can have almost the double amount of militia compared to infantry; and two militia will defeat one infantry in many circumstances.
It is amazing what you can do, or your opponent can't do, when they can't see you! Lay ambushes, take provinces without him seeing any troops coming, quickly take back a province he just took by standing aside for a minute while he rushes past without seeing you, attack lone units, move troops into position while still at peace without causing alarm, and it doesn't even end there. Of course having stealth doesn't mean you automatically can't be seen though; so you'll have to stay away from plains. Furthermore, you can't come close to armored cars (a very popular unit) or motorized infantry (much less so) when they are at your own level; and when the enemy he is very active, he may see you by patrolling his fighters as well. Now that sounds like a lot, but there will be plenty of opportunities to develop your amazing qualities!
3) often overlooked: GREAT upgrade features
Militia has only four levels available; and if you think that is bad, really it isn't, because it means that the increase of power between levels is much steeper than for other units (other notable units are rocket artillery and jet fighters), so upgrading or researching the rewards are much higher. An example? Well, lets compare them to infantry again. L1 infantry has its most important stats (off.soft, def.soft, off.lightArm, def.lightArm) at 3.0-4.5-1.5-2.3, while L2 is at 4.0-6.0-2.0-3.0, so upgrading an L1 infantry to L2 adds about 33% in combat value (usually not making it worth it, but that's another discussion). Armored cars? 3.0-4.5-1.0-1.5 goes to 4.7-7.0-2.0-3.0, that's a bit more than 50% overall. Other many-steps units are very similar to those. However for militia, it goes from 1.7-2.5-1.0-1.5 to 3.2-4.8-1.7-2.5 - in other words, it almost doubles combat value! Add to this that it is a very quick upgrade (about 20m I think, as opposed to several hours for most units), PLUS there are even less vicious units around to spot you, and it is absolutely worth it to both upgrade militia and build new ones.
What this means? For L1 infantry vs. militia, infantry is a bit less than twice as strong (see above figures). But on day 8, L3 militia and L4 infantry become available (and you spent more time and res researching the infantry, but eh). When you compare those, (L4 infantry is at 7.0-10.5-4.0-6.0, while L3 militia 5.8-8.7-3.0-4.5), most of that advantage has evaporated - militia is only slightly less effective, while infantry is over 60% more expensive. One step further, if you have the militia blueprint, L4 militia gets even better than L5 infantry.
Yes, militia are slow. When you are on the move, you should really never stack them with any other units, with the possible exceptions of AT and AA. You can't really use them in your main combat stacks; they should mostly operate alone or in small groups, often away from the main battle zone. But part of that slowness is offset with stealth: when your enemy sees your troops entering his province, he can respond there and then, and send a defense or relief force, for example. When miltia has sneaked in, he doesn't know the prov is under threat until he sees it flipping sides - that may not be speed, but it will certainly be unexpected.
5) manpower cost:
this is actually the biggest drawback of militia. While resource cost is very low, manpower cost is almost the same as other units - and manpower is often the determining factor for the growth of your army, especially in a long game. In the early game, resources are more limiting than manpower, but this gradually shifts to manpower shortages in the course of the game. You WILL need recruiting centres when you use militia extensively - and those are also competing for food and goods. Nevertheless, build them as early as you can - not just in your core cities, but in the non-resource rural core provinces as well. The longer you have them, the more total manpower they will yield.
When the enemy is driven back, we have failed. When he is cut off, encircled and dispersed, we have succeeded. - Aleksandr Suvorov.