(Picture semi-related, it was the most offensive 40K thing I had on hand. That didn't involve nudity and/or rape and/or Nazis, I mean. Or Angry Marines, because those guys need to find a new gimmick.)
Offense and Defense. At any given moment in 40K, you are doing both of them- trying to kill the enemy while trying to minimize your own losses. In another sense, however, you are generally more focused on one than the other- perhaps we might better term these roles "aggro" and "control" (as in magic), or "dominant" and "subordinate" (in terms of who the current board position favors), or "aggressive" and "passive," or any number of other terminologies. However, in the end, it's all the same- one player is satisfied with the relative positionings of the armies and is content to maintain them to his/her advantage; the other player is seeking to change the ranges. Almost always the latter player is trying to close the distance between the two armies, either for purposes of shooting or for assaults, though in rare situations this isn't true. And, of course, there is all the tactical maneuvering that occurs as part of the normal battlefield antics- this also we will ignore because, while it is incredibly relevant to the game, it takes little part in the concept I am going to attempt to communicate here.
I am going to settle on "aggressive" and "defensive" as my labels for the two parties, although that isn't exactly perfect, it's close enough to describing the dichotomy between the two. Let's define them:
- The Aggressive player is interested in altering the battle situation from how it stands by changing the relative geography. They want to maneuver to (usually) close the distance between the two armies, as they are the one disadvantaged by the current positioning due to shorter-ranged guns, melee focus, special rules, etc. They suffer the burden of movement.
- The Defensive player is interested in maintaining the current state of the battlefield, in particular the engagement distance. If they are maneuvering for distance, it is to negate the aggressive player's own maneuvering so as to keep the status quo. They are the player who stands at an advantage with the current positions, usually thanks to superior range/reach.
That's the very basics of the thing. the aggressive player is the one advancing, the defensive player is the one retreating to negate that advance. This is something you've probably seen lots of times before- Space Marines weathering a hail of fire from Guardsmen to get into their lines, for example, or Tyranids diving facefirst into Tau positions. Many armies default to a particular role because of their overall strategy- IG and Razorwolves, for example, are both naturally inclined to play as the defensive role, as they do well at extended ranges. Daemons and Orks pretty much HAVE to play as the aggressive player, as they don't have the range to function defensively against most armies.
However, sometimes things are not so clear-cut. What happens if Tau fight IG? Both of them are naturally inclined to play on the defensive end, but when matched up against each other, this may not work out. Similarly, if Tyranids (typically an offensive army) fight Daemons (likewise), we end up in an odd place. Cases like this are where the theory becomes interesting- one force or the other gets slotted into managing a nonstandard role. In fact, this is the meat of the idea- in a given fight, it is CRITICAL that you understand whether you are the aggressive player or the defensive player; mistaking your role will cause you to play incorrectly and probably lose the game.
Let's go with an example. The other day, I played a Space Marine army (admittedly not ideal) with a pair of Dreads, an Ironclad in a Pod, Khan + Bike squad, a Thunderfire, and some Tacticals. I was playing my usual "casual" army with two sets of Prime + Bonesword Warriors, two Devilgaunt squads, a ton of Hive Guard, and two Harpies. The match was Spearhead/Annihilation and I won the roll for picking turns. After thinking for a second, I gave him the first turn. He deployed deep into his table quarter; I did likewise, shielding myself from outflankers. The game went pretty badly for him, as I simply sat back on my side of the table, killed his Ironclad and Drop Pod when it came down and did likewise to Khan and his bike retinue. Realizing his mistake too late, he drive his Tacticals and Dreads forward, but was unable to get enough KP to overcome my early lead. After the game he remarked "I was expecting you to advance into my side, I didn't realize you were an all-shooting Tyranid army." My reply? "I didn't need to."
In that situation, I was the defensive player. Despite his having several long-range guns with the Dreadnoughts and Thunderfire (as well as the Missiles on the Tacticals), I knew I could score two easy KP off his Ironclad and Pod when he brought them in, and likely two more from Khan plus his squad; meanwhile, he would have to struggle to get anything from me- two fifteen-strong Termagant squads and the Warriors + Prime are each rather difficult to bring down at range., as are the Hive Guard. Confident in my ability to score KP off him (and more from the Rhinos if I got to 24"), I realized I could just sit back and wait for him.
Effective weapon range plays a big part of determining which army is aggressive and which is defensive- a Tau army with nine Broadsides (range 72") will function very differently against IG than one with just three Hammerheads, since the firepower output at that distance is less. If the IG list is one of the internet-popular Meltavet Spam armies, its effective range decreases to 12", and suddenly IT becomes the aggressive army against Tyranids, GK, and other nominally midrange armies. Likewise, Grey Hunters (12") are the aggressive unit against Tacticals (24" with MM or 48" with Missile), but defensive against Daemons (6" charge).
Now let's make things a little more complicated: whether you're the aggressive or defensive player can change over the course of a battle. Oftentimes this happens at the end of a battle when you have been playing defensively and you need to shift gears and force the enemy off objectives- but it can also shift when portions of the enemy's (or your own) firepower are destroyed in a way that changes to relative strengths. It is also very common in KP games for this balance to shift when one player comes under the burden of pulling ahead on KP or losing- if Tyranids manage to down one or more Eldar transports, for example, they often are content to simply sit in place and absorb shots while being a small amount ahead, forcing the Eldar player to engage them directly or lose the battle.
Why is it important to know which role you're in? Because movement, for virtually all armies in the game, lowers your firepower output. VERY few armies can move full distance and still shoot to maximum effect- even Dark Eldar have to limit themselves to 6" if they want to use units inside transports. This is one of the big tactical choices in 5E- do I maneuver for a better position or take shots and hurt the enemy now? As part of this decision, knowing your role is all about being able to see how badly your opponent can hurt you from his current position, and thus whether you have better firepower (defensive) or worse (aggressive.) If you currently have better firepower, it is likely you want to stay in place in order to maximize it- let the other guy move forward and lose shots. If you have worse firepower, you NEED to change that situation or you are going to lose- unless you think you can sit on objectives and win or whatnot, of course.
While I would like to write a fancy summary and wrapup for this post, time forbids my doing so and still arrive at work on time tonight (and Kirbs wants a post up.) So, uh... the final ten minutes will be self-study. Match up some army lists and figure out which one is the aggressive and which one the defensive army. Posit how that could change with different table setups/missions. And stuff.
