Fast Attack happens to be a FOC slot that many armies either take full advantage of, or they don’t even tough it. This has everything to do with what your list looks like and how you plan to play said list. Fast Attack units usually can be separated into two sections: close combat and guerrillas. In reality, you kind of want to think of all (well, nearly all) Fast Attack choices as guerrilla units. They excel at attacking swiftly, and then finding protection or attacking swiftly and hope they did enough damage that they don’t die next turn. I’ll separate these off and talk about both.
This, generally, is where you see the bulk of Fast Attack choices on the table falling under. For obvious reasons, their specialty is close-combat. However, these units are also generally less powerful in hand-to-hand than an Elites choice that would be chosen for the same purpose. However, what they lack in power they make up for in speed. A Fast Attack infantry unit will, in most cases, have an 18” assault range (either 12” or 6” for movement and 6” or 12” assault). This enables them to get into combat earlier, and thus neutralize a potential key unit on the enemy team. A good example of where this is useful is if you are a Space Marine player with an Assault Squad. Your enemy is playing as Eldar and they have a Dark Reaper team hidden in some cover. Attempting to out-shoot these units to death can be costly since you are sacrificing shots that could be used to take down assault units such as Howling Banshees and you have a very low chance of killing them as you are against a 3+ armor save plus a probable 4+ cover save if you happen to be shooting with AP2 or less weaponry. However, if you are able to Assault these Dark Reapers, you neutralize their strength (killing marines with their AP3 guns o’ death) and simultaneously take advantage of their weakness which is close combat. This idea can be applied to many more similar situations and is how you tend to see Fast Attack close combat units played.
This particular division of Fast Attacks, while still applying to the Close Combat division somewhat, takes the most advantage of the biggest strength these units have: speed. No matter what your Fast Attack choice, if you are not darting around the field every turn, you’re doing something wrong. This applies even more for Guerrilla units as their mission is to get in, put the hurt on, get out. It’s a cat-and-mouse like game where you are the mouse that’s toying with the cat, but hiding just well enough so the cat can’t get you back. It’s all about positioning both your unit and the rest of your army. Guerrilla units never (or, well, rarely) succeed on their own. They rely on other units providing just enough distraction to the enemy to make him question what is more effective to destroy, the guerrilla unit or the other dangerous elements of your army? Not only that, but the other units often provide passive protection for the guerrilla. How? Well if you are able to position your unit correctly, the enemy will be in a lose-lose situation. If he kills the guerrilla he will end up getting shot to pieces or eaten up in close combat by another unit, however if he kills those units the guerrilla will be free to roam and wreak havoc elsewhere. It is a very frustrating situation for your opponent, and one that will be advantageous to you no matter what he chooses.
In closing, Fast Attack units have one general strength, and that’s speed. If you are not constantly taking advantage of this or your list isn’t able to provide enough protection and support for these units you need to either re-think your list or just ignore Fast Attack altogether. After all, they’re not for everyone.
Only one more section to go, Heavy Support! What are your thought not only on this section, but all of the rest? Is this shaping up to be a useful article series?