This walkthrough was written based on my several playthroughs of Casualties of War I. Critical information is in bold.
I tested the campaign most thoroughly on Medium, and Easy and Hard to a lesser extent, but I'm sure the campaign is beatable on Very Easy and Insane.
I'm an interceptor-oriented player. If you hate flying in the interceptor role, you may run into problems following advice given in this walkthrough.
Notes About Ships and Weapons
GTF Aurora: Interceptor fighter. Seeing as the Aurora will be available for many missions, it can be regarded as the mainstay fighter in CoW. Keep in mind that its second primary bank has four mounts. I usually put a Prom S or a Subach there. It can't carry the Maxim. Its two-gun bank is very accurate (here comes the mandatory TIE Fighter analogy).
GTF Daedalus: Take the Aurora whenever you can, unless you need the Maxim, in which case switch to the Daedalus. It's more maneuverable than the Aurora, but overall, the Aurora is a far better fighter. It has only four primary banks.
GTB Phoebus: Excellent bomber, with a huge secondary bank, a unique ability to carry the Tomahawk, and thick shields and armor. Its only setback is its primary reserves. Much like the Aurora, it has six guns.
Subach HL-9: Good all-arounder. Bring an Aurora with Subach HL-9 in its four-gun bank for dogfights. Due to the HL-9's miniscule energy requirements, you can keep firing forever, and its firepower is acceptable.
Banshee X: Despite its name, the Banshee X is a subsystem disruptor cannon. It excels at burst damage, but if you want to sustain your damage , take the Akheton. I prefer the Akheton, to tell the truth, because the Akheton is much more energy-efficient. If you use the Banshee, I suggest maximizing your primary recharge.
Gauss Gun: A powerful primary weapon, with a shudder effect. Don't use it like mad if you want to hit anything. Its energy consumption is comparatively low.
Maxim: The Maxim in CoW1 has gone through an upgrade. Now it's a lot more useful against shields, and as such, fighters. With the two-gun primary bank on the Daedalus, you can fight effectively against fragile Vasudan fighters like the Thoth or the Horus (See the "War Games" mission).
Mission 1a: Spy Games
Stay away from the Maxtor. It will go down no matter what. You'll then be ordered to scan an Isis. Press F12 to target it. You'll also see that a Mentu has jumped in, along with some Horus fighters. Order your wingmen to defend you (C-3-8), and scan the transport. Be careful with those Horuses: They've got Morning Stars and pound you to death if you don't ask your wingmen to cover you.
Then, with all power on primary recharge, attack the Mentu. Don't waste your secondaries on it, as you'll need them for mission 2. Destroy its rear AAA turret, then order your wingmen to attack it. You aren't in a particular rush to destroy it. The campaign will red-alert to the next mission.
Mission 1b: Needle in the Haystack
The cargo you're looking for is in Container 1, which can be found to your right. Scan the container, then disable the freighter (two engine subsystems). The Banshee eats up a lot of energy, so divert all power to primaries.
From here on, it's all dogfight. Don't approach the Queb or fear for the Fuchida (your Faustus). Order your wingmen to defend you and march for the incoming FAA fighters, without afterburners to make sure your wingmen won't fall behind. The Fuchida and the Queb will jump out soon, leaving you with some FAA fighters. If all three of your mission goals are fulfilled (Press F4) and you receive the RTB order, you can progress in the campaign.
You'll be ordered to defend the other civilian freighters, but there'll be no viable reward in saving them. There will be some Ptahs around as well, so watch out.
Mission 2: War Games
The game actually checks the distance between your fighter's and the transport's "center," so disable subsystem targeting with Shift-S. Match the transport's speed and forget about your afterburners! Fly smoothly and slowly. If you think you need to fall back or gain some more distance, decelerate and accelerate using A and Z, respectively. Pay attention to your distance at all times. It's safest to stay within a range of 1200-1400. The transport will take a 180-degree turn twice, moving 150-200 meters backwards. As soon as you realize it's turning, stop your fighter. If you fear it will get within 1000 meters, turn around and accelerate a bit (no afterburners or full throttle, else you'll get out of radar range easily). Keep following the transport from a safe distance, and you'll detect a new target within range. That's the Queb, the Typhon-class destroyer you're looking for. The "Follow Transport" directive comes true, which is an indication of your success in the mission's first stage. Now you can forget about the transport. Command may yell at you sometimes when you get close to the transport, but the transport won't bail after the "Follow Transport" directive comes true.
Stay outside the Queb's firing range, and destroy its Weapon subsystem from afar with your Maxims. Once it's down, tag the Typhon to call in your task force. Sometimes you'll need to tag the Typhon twice or three times. It's important to destroy the Weapons subsystem before TAGging, because TAGging will trigger your task force's arrival. The Patchet, a Sobek, will threaten your destroyers the most, but destroy its Weapon subsystem is optional if you destroyed the Queb's Weapons before the task force's arrival. Once that's done, all you have to do is to participate in the dogfight and get some kills. Stay away from the Patchet's flaks and there won't be a problem. You aren't expected to do wonders at this stage - You've already done your part.
Mission 3: Halfway Between Heaven and Hell
I suggest swapping the Gauss Gun with something else (my preference here is the Subach).
Target the nav buoy and head towards it. Like in any "follow the nav buoys"-kind of missions, the next nav buoy doesn't get within sensor range unless you're close enough to the current one. It's better not to use afterburners, because your wingmen will fly without afterburners. You can use time-compression if you want. Before Nav Echo, you'll detect some hostile targets dead ahead. Wait for your wingmen and head towards the enemy. You'll face two Mentus, one Setekh and 4 Serapis fighters. Attack the fighters, then do as much damage to one of the Mentus as possible. 4 new Serapis fighters will jump in. Reissue the "Defend me" order (C-3-8) and destroy them. A new wave will jump in, but let your wingmen do their job until you scan the AWACS. Destroy the remaining fighters, let your wingmen take care of the remaining Mentu(s) while you disable the Setekh. Hopefully, your wingmen are already done with the Mentus. Order them to help you with the AWACS.
The mission won't break if you don't follow this sequence of targets. You can take care of the AWACS first, but the Mentus may fly out of your radar range if you take too long.
Mission 4: The Tempest
This isn't a complex mission, but you've got to be careful nonetheless. Start with destroying the two forward beams of the Sobek using your Trebuchets (one rocket per beam). Then attack the Sekhmets until they are depleted. You may come under attack by some Scarab stealth fighters, who EMP-shock you using their Banshee Xs. If you're hopelessly disoriented, order your wingmen to defend you (C-3-8). From here onwards, keep massacring the fighters until they run out of reinforcements. Some transports (Hygeias and later Argos) will emerge from the Tempest's fighterbay. The Hygeias won't come under attack, and the Argos aren't in real trouble if you're any good. Losing one Argo is still tolerated.
Mission 5: A Fox in the Henhouse
This mission is long and there's a lot of dogfighting.
Hand out all available Auroras to Beta and Gamma (reinforcements), and arm them with Subachs and Prometheus S, with Prom S being on the second, four-gun bank. The Daedalus is no good for this mission. Prepare against fighters, a lot of them. You don't get a penalty for calling in Gamma, as far as I'm aware.
Scan the containers, row by row. Four Serapis fighters will ambush you, but pose little threat. You can use time compression to accelerate the scanning process. If the enemies jump in, you'll have enough time to reset your time compression and get to the action. Taurus wing will attack the freighters; Leo will attack you and your wing.
You don't have to defend all three freighters. Two will be enough. Don't forget to scan all the containers before you jump out. If you destroy the Taurets before the freighters jump out, use time compression.
Mission 6: Dante's Inferno
I suggest the Aurora with Subach HL-9s in both of its banks.
Get the Thoths, press C-3-9, and tell your wingmen to ignore the station. When the sentries are down, an Isis transport will be launched from the station's hangar. Don't attack the Isis. Get back to the Tempest, and wait for the mission to progress. It may time some time, but the mission will progress.
Sobeks, Mentus, and Atens will jump in, escorted by fighters. A rather confusing battle ensues, but all you have to pay attention to is to stay away from the AAAs. Get some more kills out of the fighters, attack some of the Mentus, then let the warships duke it out.
Mission 7: Breaking the Wall
The mission requires you to take down a lot of beams, but I actually suggest going right for the kill. Give Phoebuses to either Beta or Gamma, arm them with bombs, yourself with all-Trebuchets. Or get bombs and help in the kills. While the Phoebus can carry the Maxim, I don't recommend that you take them on larger difficulty settings, because the Phoebus's primary reserves are low. Remember that one Trebuchet per turret is enough.
Alternately, you can carry the Maxim/Akheton/Banshee and destroy all three Sobeks' forward beams. Fly low, avoiding flak and AAA fire. With an Akheton (or Banshee) in my upper bank, I managed to destroy all forward beams in two minutes. You don't have to concern yourself with the Sobeks' rear AAAs.
Once the Sobeks are down, or severely weakened, get the Atens. Watch out for their AAAs. Remote-bombard their rear and bottom turrets, then finish them off by attacking from below. Once the Atens and the Sobeks are destroyed, some Mentus and a Hatshepsut (the Apep) will jump in. The GTVA has the situation under control at this stage. The Apep will escape when the Agrippa, a Hecate-class, jumps in. The Mentus are easily destroyed by the Agamemnons.
Mission 8: Revenge
By default, you and Alpha 2 are Phoebus bombers, armed with Tomahawks. Your mission: Take down the solar panels. Mount Tomahawks into both your secondary banks, and go. You can also mount a Maxim into your upper primary bank if you want.
Rush towards the station, and don't pay attention to anything else but self-defense. Fire one Tomahawk per solar panel. Fire one Tomahawk and change bank. Tomahawks are very fast, and are not in danger of being intercepted by the station's point-defense systems. You can be done with it alone in two minutes. Once all the solar panels are down, fly for survival and pay attention to your directives window. An Isis will arrive soon. Scanning it is a must.
In the ensuing battle, you are expected to help the warships against the Sobeks. Pay special attention to the Tempest, as it is in the greatest peril.
Note that the Ogdoad's solar panels are registered as "AWACS dishes" in your target view.
Mission 9: Casualties of War
At the first glance, this is a daunting mission - another large-scale battle. However, it's not as complicated as it appears. Ignore all the warships, as if they weren't even there. Your mission is, as it's said in the briefing, to disable the Apep. No more, no less. I'll tell you a huge secret in advance: The GTVA warships are gonna win without Alpha 1.
Give Auroras to Gamma. Any dogfight configuration will suffice. You don't have to take Akhetons or Banshees, either, because the Apep has the "big damage" flag and you have ample time to disable the Apep.
Fight your way through the Apep's fighter screen slowly but gradually. You can use time compression when on approach. Tell your wingmen right on start, as soon as all of them jump in, to defend you (C-3-8). Head directly to the Apep. Don't deviate, else you get AAA'd. You can take a shot at the bombers, too, but they should be your smallest concern. If some of your idiotic wingmen get too close to the Sobeks, tell them to form on your wing (C-3-7) and get out of range. Remember that C-3-7 makes them ignore any danger: As soon as the next wave of fighters get within range, press C-3-8. Don't worry about losing some of them: there is more than one wave. As soon as you destroy all of the Apep's fighters (there's a message about it), tell half your squad to attack engine 1, the other to attack engine 2. You can choose to participate or not. The Apep is turret-locked, so the biggest threat to you is collision damage.
As soon as the Apep is disabled, you're done. Watch how the campaign ends, then jump out.