As you progress through the DoR Campaign many of the levels and maps you play on are pre-deploy maps, meaning that there are no factories, ports or airports to produce units with, forcing the player to use the units that they start with on the map. The reason that this is, is to force players to use a certain style of play against the AI, and it makes the game more challenging (if you're not far into the campaign, I might add IMPOSSIBLE). Sometimes on pre-deploy maps your enemy has the advantage of actually having unit producing infrastructure, so so start your outgunned, and then outnumbered.
NOTE: Throughout this post, when I say pre-deploy map I mean maps that have NO unit producing buildings at all, as opposed to maps with neutral producing buildings that can be captured as the game progresses.
Sometimes we get lost as to how to use our units on pre-deploy maps, because if you lose that Md. Tank there's no way to get it back, you can't use factories, so we become a turtle and run away, that's probably the worst thing you can do. Allowing your opponent to gain ground on you, while you have a limited number of units spells certain death. You have to use tactics to hit your opponent, then quickly get out of harms way. Exploit weaknesses, figure out what your opponent does to counter your moves, and come up with a style to counter that. Does your opponent hit you with surprise attacks from artillery, or does he smash you with tanks and infantry? Does he try to surround you and pick off your units, or does he lack aggression?
All of these factors must be considered when you are trying to conserve your units. Another extremely important thing to remember is to keep your infantry units alive. Even if this means sacrificing all of your best and most powerful parts of your army. Why all this for a poorly animated infantry? Well on pre-deploy maps we usually don't try to win via annihilation we try to capture our opponents HQ. And you can't do that without foot soldiers. If you have transports, load them with your mech and infantry, as they are safer in here, and have more mobility. Get a convoy going, this is what I usually try to base mine around:
2 Infantry Units
1 Rig
2 Recons
1 Tank
1 Artillery
Try to keep the stronger units on the outside, and the more fragile and important units towards the inside, almost forming a circle of protection, or as I like to call it: Sprite Night. Move your convoy down the map, and make sure to keep a couple units guarding your HQ. As your convoy advances, fend off any attacks as best as you can but don't ever stop to engage enemies that you don't have to, let them come to you. Once you unload your infantry on your opponents HQ, the convoy doesn't become useless, and go shoot at infantry on the mountains, they engage in their most important job: "Capping" the HQ. I believe I explained this in an earlier post, but let me draw some beautiful ascii art to vaguely explain the concept, then let me explain in words.
TANK/RECON
INFANTRY/RIG HQ/INFANTRY ARTILLERY/RECON
Uncase you didn't understand that, the HQ/INFANTRY in the middle represents an HQ with an infantry unit capturing it. The units to either side represent the units that would be surrounding the HQ. So the TANK/RECON above the HQ would mean you position a tank and recon unit there. Try to position your strongest units, so that they are facing the enemy. For example, if the majority of your enemies units, or their stronger units are at the west, put your tank and artillery on the west side of the HQ.
The purpose of capping an HQ is to hold off your opponent for long enough (2 days) to allow your infantry to capture the HQ without being harmed.