Terran Strategy, Lesson 2: Combined Arms
by mrxak

Note: Combined Arms is not for rush games. Rushing has a completely different set of strategies, which I will briefly touch on in another lesson.

In real-world military terms, combined arms is the use of many different types of units, to defeat your enemy easier, and with less friendly casualties. The first step in using combined arms effectively is to understand this concept, and visualize it working for you, or against you. I will touch on both attack and defense with or against combined arms. First up, is attack.

Recon is the most important thing there is in Starcraft, or any battle. Terrans have it the easiest, with Comsat. It also helps to have a few units on the field at certain places on the map where the enemy will have to come to attack you. The more recon you have, the better. Make sure that before you can begin an attack with combined arms, you know where the enemy is. In learning where he is, you will also know what units he has. I will discuss recon more in a later lesson.

Combined arms is one concept a lot of players unfortunately neglect, especially in terran. Too many times I've attacked a base full of only barracks, churning out marines. I'm sure those marines appreciated me annihilating them with my multi-unit attack force. The thing is, most terran players concentrate on one or two units, neglecting the useful abilities of the others. The most common units that are concentrated on are: Marines (Medics occasionally supporting), Tanks, Wraiths, Ghosts (with nukes), and Battleships. Rarely do I see any Firebats, Science Vessels, non-nuking Ghosts, Vultures, or Valkryes. It is also a rarity to find people using any of these units together to attack a target. Yes, it can be more expensive, and time-consuming but the results are worth it!

Combined arms involves a lot of what you learned in support units, but adds another concept, which is weapon damage. There are several types of weapon damage, and each has different effectiveness on different sizes of units. I won't go into very many specifics, but if you diversify, you will increase the effectiveness of your attack force on any given target group. Besides, you know better than to attack a bunch of Battleships with Firebats right? I have destroyed a number of bases, using air to destroy ground-to-ground defense units, just before I attacked with my ground. The air-to-ground units were of course guarded by air-to-air units, just in case. The air-to-air units also were good to spread the damage taken by ground-to-air defending units. In most cases, I would retreat my air as the ground units began to attack, healing and repairing them so they were ready to fight another day, or another minute.

Combined arms is less of a strategy than a lifestyle decision. Either you choose to use it or you choose not too. I'd recommend it because it will help you if you do it right, but if you really want you can always crush your opponents with waves and waves of marines. Just be sure he doesn't crush you first.

Now, good groupings are up to you to discover, but generally it is easier to deal with only two or three unit types at a time (excluding air and supporting units), than a truly diverse battle group. The only hint I'll give you is that tanks and goliaths work well together. Upgraded they both have excellent range and can deal with a lot of enemies. Tanks in siege mode and golaiths standing by to kill things up close or in the air is a very effective combination.

Generally, I prefer to have more than just three unit types in a battle group, or have several battle groups working close together with more diversity across them all, but less within each group. Air units (both anti-ground and support versus air), anti-air units (like goliaths and upgraded and/or stimmed marines), and anti-ground units (tanks, firebats, marines, vultures) is what you will probably want, but it will vary each game you play. Ghosts can fall under both anti-air and anti-ground, but mostly in support and tactical roles. Support units should not be neglected in your force, but keep them where they will do their job the best. If your opponent has little or no air, don't put too much into anti-air, but do keep up a good air force yourself, to maintain superiority, and force them to spend on anti-air (and less on anti-ground). If they have lots of air, put more into anti-air before building too much of your own air. You must destroy pretty much everything in the sky before it's safe to rule it.

Once you have built your combined arms force, send it out to conquer the map. Remember it is combined arms though, so keep your units working together at all times. If you come across something one part of your force can't kill easily or at all, use another part that can. If you come across a diverse group, kill it with your own group, using each part of your own to attack the units it is designed to kill, and then support the rest when that is done. When attacking anything, always remember what you've learned in lesson 1. Use support units well, and organize. Also remember which units cost you the most resources and time (which is also a resource), and protect them first. Marines are expendable whereas Battlecruisers are not. A Tank or Wraith would be somewhere in the middle. Perhaps using less-effective units first to soften up stronger units in a battle first is better than sending in one of your more powerful units immediately to die and take them with it. Stronger units are harder to come by, so use them wisely. The opposite goes in the reverse: Trick your opponent into losing his most expensive units against your own cheap units or against strong defenses, so it can't do a lot of serious damage against you. And remember your ghosts you have in support. Lockdown those big juicy battecruisers and carriers, and you'll kill it easily. Bring your medics along for the ride too, just in case your opponent tries the same thing on you. Simply restore the units worth saving, and draw fire (or simply kill the attackers) with other units when you run out of energy.

Careful unit control along with a diverse group can help you overcome huge odds. When confronted with multiple threats, you should be able to defeat all but the largest and most powerful forces if you are skilled enough and prepared enough. If they have air, lockdown the more powerful mechanical ones, use goliaths, marines, and bring in the air-to-air, using medics and SCVs to repair and heal. If they have firebats, blast them from afar with tanks, marines, vultures, and use air-to-ground forces as you retreat a bit if it gets too hot (more on retreating later). If they have tanks, attack with air as you retreat your ground and if there's not too many, kill them up close with stimmed firebats and fast vultures. If the tanks are spread out, you can even trick them to do splash-damage against each other. If they have zerglings, use firebats and tanks to wipe them out utterly. If they have dark templar, use comsat and science vessels to see them before they get close and hit them with tanks, air, and other ranged attacks first. You should always use EMP and lockdown against protoss as soon as they get in your range. These are just a few situations you can think about, and there are many more. Right now go into StarEdit and put a bunch or random units on the map from differing species. Think about what weaknesses they have that can be exploited easily with a diversified terran force. Try to think also of what enemy units are most common. If you can come up with an bare-minimum set of units to destroy most opposition with a good degree of effectiveness, you can use it when your recon is lacking on what the enemy has. Just remember: Air, Ground, Close-Range, Long-Range, Big, and Small. You should encounter all six at some point in another.

And what happens when you're on the receiving end of the combined arms? The best thing to do is be prepared, have combined arms yourself, and just be able to do it better. Use the same weaknesses of the enemy units that you've already discovered. Kill units with units that can kill them the easiest. Don't attack randomly or wildly. Attack-moving works only initially to make sure you engage with the full force. You should quickly begin to specialize as fast as you can. If things look bad, just retreat back to scrambled units that can do what's needed. This brings us to the next lesson.