User blog comment:Tardir/Red Crusaders Something.0/@comment-2253300-20130220223633/@comment-2253300-20130221011534

Well lets see here. I know that in general while Space Marine Fleets are formidable in every respect they tend to excel more at planetary assualts more than space battles. I also know that, unless they have updated it, they tend to lack in non-atmospheric fighter craft, usually emplying Thunderhawks, and the like. I know that they like to get up close and personal with the enemy so that they can drop the enemy's shields and launch boarding craft (Naval combat is naval combat when you are talking about ships, the Marines strength is in their infantry, so why not try to use them in space battle?). They also often board using teleporters. Being more geared toward planetary assualts they are good at orbital bombardment. Aside from that SM naval warfare is roughly the same as Imperial Navy.

Now I am not sure how much I can tell you about SM ground warfare that you don't already know. The SMs have the best armor, weapons and training available in addition to their enhancement. However the fact that they operate in 1000 man units, and more often than not do not deploy as a whole, means that in any given engagement the Space Marines are outnumbered. They make up for this by being the best soldiers in the universe, pound per pound, but it also means that there are things that they can't realistically do.

Like garrisonning a whole world. I mean, could you really see a hundred guys maintaining control over a whole continent? My guess is that in order to be able to subjugate whole planets the SMs rely heavily on fire support, and that of the planet strike oriented fleet mentioned above. In general though the idea is to deploy these elite troops where they are needed, using them to reinforce positions that are vital to a campaign, and sending Marines to hit the nemy where they are strongest, doing the most damage possible.