well, you are germany.
the trick to build a successful army as germany is one that quickly crushes all opposition by cooperation between the different army roots, the army and airforce (perhaps if possible the navy).
this is the whole point of blitzkrieg.
you should aim for the following:
Army:
_solid core of infantry, 1941 perhaps is great but if you want keep developing
_a good core of Armored units (medium armor, not light)
_a few HQ units (depending on your army, i usually get 5-6)
_many motorized/mechanized divisions, to help exploit breaches.
if you want to go with brigades, usually goes like this:
-for infantry, get artillery (makes them slower but more powerful, but then, infantry are not meant to be fast)
-for Armored units, SP-Art is the way to go (all benefits of artillery but dont reduce speed, they take up fuel though)
SIDE NOTE: on my games, i make at least 6 tank armies, composed of field marshall, HQ, and 5 Armored units with SP-Art (by the time i get them usually panzer 4's or Panthers), as this increases their already amazing speed and org regen.
-for motorized, its really optional, though if you really want to make Mot inf powerful, give them Armored cars or SP-Art.
Airforce:
_Significant number of fighters/interceptors to defend your bombers
_Tac. Bombers are great all rounders, and are great at Interdiction missions.
_CAS is VITAL to break enemy lines, as their soft/hard attack ratings are AWESOME
_strat. bombers are not necessary
Tactics:
you have to use your superior firepower and mobility to encircle and destroy enemy armies.
step 1.-
_set your infantry forces along the entire front. if you cant manage this try to keep at least some infantry forces in most areas. you are attacking, remember that.
_in one province, preferably in contact with a relatively weak link in the enemy force, set a large force of Armored units and Mot/Mech infantry.
the tanks will make the breach, while your motorized/mech units occupy the breach.
_if you havent done so already, send your tac bombers to interdiction/logistical strike, to reduce their org, org regain speed, and reduce enemy's ESE.
_pause the game if you need to and plan the blitz. how big will it be? how many armies will you trap/destroy? do you have enough men? is the enemy capable of cutting off your troops and destroy your armored spearheads?
the best time to attack is at the beginning of the day, usually 4am in areas around Germany. make sure the enemy province is not a forest or swamp, and that its not winter, since all of these things are, to put it bluntly, horribly awful to attack, but excellent to defend.
also, make sure that you use Shift to attack so your men dont have to reorganize for a day after an offensive. after a new province is taken, leave a respective numer of units (the mot/mech divisions) to guard the gained land and exploit the breach. keep doing this until you have cut off the enemy forces from their land. without supplies even massive hosts become relatively harmless and lose Org at a frightening speed.
_this is what would happen if successful. before you unpause, order your CAS to launch ground attack on the provinces you will attack, and send your Fighters/interceptors to fly air cover for your Tac's and CAS if you havent done so already.
after the enemy is trapped, begin reduction of the enemy armies with your infantry (that's what they are there for), and also make sure you hold the encirclement. if a province falls within their control again and they reestablish the supplies, not only will it be harder to kill them, but if they lose they will retreat instead of surrendering. do NOT allow this to happen. if the enemy escapes you have failed in your task to destroy the enemy.
_after the enemy pocket is destroyed, move your infantry forward, repeat and destroy your enemies
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as you see, this army (the german army) was made not to go into protracted attrition wars like Russia and (perhaps) UK and france, hell even the USA or japan. the german army's objective was to obliterate the enemy's armies and sue for peace.
this is why Germany didnt win in Russia; they could destroy entire armies of russian soldiers but they could just keep sending more men, while Germany could not replace their casualties.
i hope i was of some help