There has been a lot of discussion about how Grey Knight mech is different compared to other mech and has often been described a hybrid force, even when there are no discernible foot units in the army. This is a direct result of how Grey Knights often play with most of their basic infantry being quite effective on foot and at a pretty decent range. This is compared to most armies where their basic infantry models are either more effective up close (rapid fire), not very effective at all (older books) or very weak in durability. When we combine all of these factors with the very advantageous vehicle damage chart (minimal effect on passengers and very sturdy), cheap transports and fire points, we get what we have today; a lot of armies hiding in their transports unless otherwise necessary. And why not? You get the great defenses of the tank and can often still fire your important weapons (heavy and specials) out of the top-hatch whilst still scoring if you are a Troop choice. You're also adding mobility and potentially extra firepower so it almost becomes a no brainer of a choice.
Grey Knights however are different. They can certainly take advantage of this concept (i.e. Crowe RazorKnights, Coteaz Henchmen spam, Purgation squads, etc.) but a more common theme is to see Grey Knights willingly outside of their transports. Why? Storm bolters and psycannons (which we have discussed before). This gives the basic Grey Knight trooper ability to affect the board significantly at 24" which puts a big damper on needing to get close to the enemy. When you combine these guys into squads, they are very happy to be outside of their transports and shooting and moving all game long. This all stems from every Grey Knight model being able to impact the game at range. Imagine doing this with a full Tactical squad. Seems silly as you are losing the advantage of range on the heavy weapons (i.e. not at 36"-48") or wasting the bolter potential (not within 12"). This is the same for many other armies and generates a significant opportunity cost. Not so for Grey Knights.
Grey Knights have the further advantage of having excellent counter-attack ability and MEQ statlines. This means they don't fold like paper outside of their transports or need twenty guys to hang around. This ultimately impacts upon how Grey Knights use their transports as they are not required as much for actual transportation or protection. This is of course a fine use of Rhinos and Razorbacks and more often seen against fast armies when that extra range is needed (I'll do a post later on how large an area 24" can cover).
This greatly impacts how Grey Knight mechanised lists play in general. Rather than staying inside their transports all game (or for as long as possible), Grey Knights often aim to get out of their transports ASAP. This increases the firepower on the field available to the Grey Knight army but of course comes at the cost of exposing your Grey Knights to enemy firepower. This means it may be advantageous to hop out of your transport and use your infantry firepower but is not always necessary. An obvious example would be when you don't need the firepower the infantry provide you, in particular when you can use top-hatches. This ultimately relegates Grey Knight transports to a role of actual transportation and then fire support, movement blocking, etc. after their initial moves have placed the infantry into position. This combines very well with Fortitude as it allows them to keep moving and firing and therefore impacting upon the battlefield.
Which brings us to non-transport tanks or transports which do not often want to disembark their contents (Purifiers in Rhinos, Henchmen scoring upgrades, etc.) and the advantage Fortitude gives these units and non-transport vehicles. It keeps the army trucking along. Fortitude makes the Grey Knight mech aspect really hard to slow down without psychic defenses and therefore gives the Grey Knight army more control over the battlefield as they are more capable of remaining mobile and offensive. This ultimately increases the importance of AP1 and actual anti-tank against Grey Knights rather than suppression abilities unless there is psychic defenses around (in particular defenses which increase the chance to suffer from perils).
Conclusion
Grey Knight mech operates very similar to what many consider modern military tactics where the transports and vehicles are supported by and in turn support the infantry. In particular, Grey Knight transports are not always mobile bunkers or scoring platforms and play the role of initial mobility for Grey Knight infantry. With Fortitude available on all vehicles (excluding the Chimera), Grey Knights are able to push through minor damage and maintain board control as long as possible. Maximising the potential of this power, the good shooting ability of the Grey Knight infantry and their associated transports is key to making Grey Knight mech work. It's not always about bunkering or moving units forward but a combination of both that allows the Grey Knight army to maintain flexibility and deal with multiple forces in different ways.
