Kal and I have been on the opposite of many a debate, but here, I think he is right in every regard.
First off, sticking Space Marines in fortifications is a tremendous waste of their abilities. Sure, people may scream about how the Iron Warriors or Iron Hands or whatever are the premier siege attackers/defenders in the galaxy, but simply put, a Space Marine is *utterly* wasted sitting around, either defending something or besieging something. I will be the first to admit that they are superior shock troops, and would be the best choice for assaulting fortifications after the necessary bombardment and trench construction, but for
digging saps? Trenches? A complete waste. Why have Space Marines, quite literally, standing around digging dirt when they could be taking advantage of their mobility and combat density?
Now, considering the Guard, obviously field fortifications would play a prominent role. We do know that there are several kinds of prefabricated structures; the Bastions for Planetstrike are,
IIRC, prefabs, and the Aegis Defence Lines are wonderful, wonderful things. I'm sure that all of us have seen (in our
FLGS) cardstock bunkers with aquilae on them that might as well be prefabs. So, we know that there are prefabs, but we don't know how extensive they are.
However, even discounting prefabs, there's plenty of field-expedient defenses that can be constructed. Simply put, the Guard will be fighting on the ground, which means there's plenty of natural resources to be used. Sandbags are an obvious approach, as are the more modern
HESCO bastions. Throw in some chicken wire, logs, and razor wire, and you have yourself the nice beginnings of a defensive position. If you really want, you can check out
FM 5-15: Field Fortifications. Though, I suppose if you want, you could check out the
Vietnam edition of the same book.
The simple fact is that with the gratuitous application of the pick, axe, and shovel (or "9-70", as the Guard calls it, or E-tool, as contemporary soldiers call it), you can build a very extensive defensive network. Once you start adding in plywood, hammers, and nails (and with some engineers), you can start making some more comfortable buildings. If your logistical network is strong enough, you can also bring in prefabs, like
Quansit huts, which can apparently be constructed (it would be shipped broken down) in
about 8 days. That's not bad.
Rrrr. I've lost my train of thought. Primarily because I'm now on a war grognard kick. I'll check back later.
edit: Concerning Kal's statement about permanent fortifications becoming essential parts of the Guard supply chain (or whatever it was): Mmmhmmm. 100% agree on this. Granted, I'm not sure where the Munitorium's job ends and the Guard's organic logistical assets begin, but I'm fairly sure that supply stocks would need to be concentrated and protected. Now, the part that would interest us would be a Forward Operating Base (FOB), which is a combination supply dump, command post, barracks, Forward Area Refuel and Rearm Point (FARRP), and whatnot. Not all in the same building, obviously; it would be a compound a couple of square miles big. Hee. Anybody else find Defencell's
"FOB in a Box" to be a funny name? Anybody?