From: Rio Grande do Sul
:: WARNING! WALL OF TEXT ::
The missions is not that hard. Just old pike and bow tactics, but start expanding your tanks force. Double it in the next two scenarios. If you can afford it start training new aircraft as soon you hit the exp cap. Polish air force is quite weak which a good environment to train recruit pilots. You don't want to do this later when facing veterans piloting modern planes.
Back to the mission.
Overstrength both Wehrmacht infantry if possible. Place your most experienced Wehr-Inf. in Piatek (13,12). The other goes to Ozorkow (7,16).
These two cities will see most of the action. The higher ground defense of the Wehr-inf. will help against tanks and arty fire later.
Try to overstrengh two of your Gebirgsjager troops. Place one at the forest (11,14) to defend this river crossing. The second units goes to (20,15) and then moves up to forest at (19,11) to the defend the other river crossing.
Buy now a 88mm Flak and place it at the crossing at (17,10). When it's your turn again switch to at mode and move it one hex SE to (18,11). It should earn quite some exp reaping tanks foolish enough to attack this crossing. In later scenarios you can use the 88 to attack bunkers in Norway and the Low-land campaigns.
Place the 10.5 Arty south of Piatek and move it to (14,13) to backup the city defender. If you can afford it buy an other Sturmpanzer and place it south of your 10.5 arty to defend it from river crossing units. If you can't afford you will have to move you're arty around to avoid being rushed.
A Panzer 38t goes to (15,12) to defend the arty and attack crossing infantry.
Your other two Sturmpanzers go to (11,15) and (18,12) to backup your defenders there
Place the other two Panzer 38's together with the Recon unit in the east. Use the tanks where they are need. The initial assault on the eastern mapd edge is quite weak. You may use your tanks to cross the river and flank the attackers, but don't venture north of Bakow Gorny (20,8) nor west of the Bzura Bridge (17,10).
Use your recon unit to recapture taken bridge hexes and then move out again in the same turn. You don't want your units get caught on a bridge. Units receive a large penalty on bridges. Wait I think it was the other way around. You get a bonus for attacking units on bridges/rivers. Either way it's bad. Press L to see the combat logs and learn about the modifiers.
In Lodz (11,23) you will find 3 at guns and a arty piece. Place on AT guns at (8.16), Hill at (10,15) and the Forrest (13,13). The arty goes to (8,17).
You find an other AT gun and arty next to the city of Lowicz (25,10) leave the arty where it is but move the AT gun into the city.
The enemy will start attacking Piatek and western hexes. Later the attack will shift to the east. Depending how good you're doing you can move your arty defending the bridge at (10,14) to the eastern bridges. Now let the enemy come to you. Hit units next to you're defenders with the arty to stun them before attacking. So that you always takes little or hopefully not damage in doing so. Watch your ammo levels! Never let any unit go below 2 ammo especially arty. Take an exception to this rule in emergency situations of course.
Priorities your Air force to attack units in that order. Units crossing the river and threatening your position. Tanks then Arty.
Word of advice if you plan to play the grand campaign to the bitter end at 1945 don't use Stukas. They need babysitting all the time or they blow up. Instead use Fighter Bombers like the BF110. The difference in ground attack is negligible but the ability to effectively defend and attack other airplanes becomes crucial when you later face powerful and experienced air force.
While your fighters engage the enemy fighters, your fighter-bombers can dispose the bombers or finish off already weakened fighters.
BF-110's also have a very nice upgrade path, all way up to the powerful Me-410. Try to overstrength your planes. Its rather cheap compared to overstrengthing tanks and greatly boost the planes performance.
The opposing air force always attack in waves. With a figher, figher-bomber combo you can quickly dispose a wave in 1-2 turns and then have up to 3 to 6 turns of clear airspace to bully the enemy at leisure. At my second playthrough at the end I always deployed 8 fighters and 5 fighter-Bombers. But I had actually 10 fighters, 8 fighter bombers and 5 strat bombers. As backup should I lose a plane. At the end recruit planes stand no change against the AI elite fighters. Either you have backup replacements, cheat or use ground AA units instead.