Been addicted to this game for too long so here is my one way to beat it. Last two campaigns lost 63 troops for the whole campaign.
1. Beach. Pick top or bottom. Send assault troops within 1 second of starting. Prepare bazooka but hold back for a few seconds until your resources refreshes to 700. Send bazooka and then riflemen immediately after (all down the same track) The rifles will overtake the bazooka and support the assault troops. There is a very small window to protect your bazooka. If you send them too late they will be bombed on the beach, too early and they will be shot at the sandbags. As soon as you refresh to 300, send assault troops on the other wing. This will draw some of the bombing and machine gun fire away from your bazooka and supporting soldiers. Next 200 send rifles up the middle. After that it doesn't matter so much, but I usually send another rifle unit and a bazooka. You should get 4 upgrades plus 40-50 credit from this round. If you don't, quit to main menu and try this level again. Use your 4 credits to get 10% defence, 10% attack, faster reinforcements, and grenades.
2. The secret to this level is to advance 3 levels of troops in a line, and take the log quickly, using grenades. Click assault top, rifles bottom, and when it refreshes, more rifles up the middle. Let the wing men wait until the middle rifles catch up, then advance as a line.
Use your assault troops to take out machine gunners behind log with grenades before you die too much, but at some point soon you need to save enough resources to send another unit of assault up the middle, to help out. This should be enough to get you through the middle if you have acted quickly and with co-ordination. Use any remaining resources for throwing grenades. You need to let your little man finish throwing each grenade before you press to throw again, or he just scratches his tummy. Some upgrades are allocated for killing people, but you tend to get ones and twos, and the 75 points you sometimes need for one upgrade are hard to come by. Finishing the level quickly tends to get you more upgrade points than struggling, killing lots of soldiers, and taking a long time. You should get 3 upgrades. Use two to increase reinforcement time again, and save one for later.
3. The Germans always send a mortar man in the bottom right, and protect him with lots of soldiers. The secret to this level is to advance quickly at the flanks, and try to take out the mortar man with grenades and advancing troops before he is covered by other troops. Click assault bottom, rifles top, then when refreshed more troops down the middle. Get your troops over the first fence quickly before being bombed. Follow up with troops down the middle, also taking the flanks if you can, I suspect this slows down German reinforcements. If you take this level quickly you should get another two reinforcements plus the one you have saved. Use this to buy cheaper reinforcements for the tank level.
4. Tank level. Send a bazooka straight to the wall at the top. Don't worry too much about being overrun by troops- the bazooka in cover is actually quite effective against advancing troops. Send assault troops straight to the stone wall on the bottom, with riflemen at the barricade just behind. They need to get there in cover before the first tank starts shooting. Send another bazooka to the first barricade at the bottom. Wait until your assault troops start engaging the tank, by which time half of them will be dead. Assuming you have bought cheaper upgrades by now, you should have quite a lot of grenades. Throw grenades from cover at the tank for all you are worth. The tank will come under fire from two bazookas and multiple grenades, and should be blown up before it reaches the line of the assault troops. From this point you need to manage your resources to replenish what you have lost. If all your assault troops are dead, move the riflemen up before the next tank approaches, and bring fresh assault troops in behind. If your top bazooka is dead you may need to retake the top wall with assault troops, and bring on a fresh bazooka behind. This is much much harder if you have not got up to cheaper reinforcements, but can still be done.
5. Hedgerows. In this level, the Germans use a sniper behind massed troops to effectively pick off lots of your troops. I have found that although the advice is to advance up the hedgerows, if you are on cheaper reinforcements you can send assault troops, riflemen and then a machine gunner up the middle, using grenades to take the central blockade, and as a base for bombarding oncoming Germans. You need to find the balance between grenades, bringing on perhaps one more set of reinforcements, supporting your men from cover, but also advancing as rapidly as possible to get maximum bonus points and to take the middle line before you get overwhelmed by German reinforcements. The most useful upgrade for the next level is faster tanks, and you have one left over which you could use for mortar accuracy which will be useful in the level after that.
6. Open range. The combination of tank plus bazooka is surprisingly effective because the tank draws fire away from your bazookas, even if they are in front of the tank, allowing them to get 2 or 3 shots into the opposing tank. You need this as pound for pound the German tanks are better and will defeat you. This level is again hard to win without cheaper reinforcements. I would send a tank straight up the middle, then bazooka, then assault troops. Use assault troops to throw grenades to kill the opposing tank quicker in combination with your tank and bazooka, but also to throw grenades quickly at opposing bazooka men before they damage your tank. After you have taken out the opposing tank, mass assault troops and riflemen up the middle, using your tank for cover. With your upgrades, make sure you have increased mortar accuracy, and if you have another two left over, get increased flank attack.
7. Graveyard. I like to stick a mortar in the middle first thing, then advance troops up both sides quickly jumping over the cover. Experiment with troops up the middle - riflemen, assault troops, machine gunner or sniper all have their advantages. Use grenades and keep advancing your men, although time this so that they pause behind cover if engaging oncoming enemy. At the end of this round you may not have enough for a useful upgrade - The next most useful one is tank machine gun +30% damage. You may have to start the final step without this upgrade, but as soon as you see upgrades increase to 2, click on it, and get the tank machine gun crew upgrade.
8. The final step. Send a bazooka up the middle to the wall, hopping over the wall when he gets there to get to the barricade in cover. Meanwhile scan the opposite end to see whether their tank is coming top or bottom. Put your tank opposite it to oppose it. Support your tank with assault troops, and use your bazooka in cover in the middle, tank and assault troops throwing grenades to take out the opposing tank. Start throwing troops up the middle and keep them moving as enemy artillery seems to come from nowhere. Meanwhile use your assault troops ahead of your tank to take out any bazookas with grenades. If you keep your tank alive, it will clear the middle lane of enemy troops, which normally amass quite heavily, and allow you to throw troops up the middle. You need about three units of rifles/assault troops, with grenades, going up the middle supported by the tank, to get through the middle and take the final bit.
This approach works as at late August 2011 but I know the settings have been tweaked from time to time, so good luck!
