I played the game once again against Dave. I was playing the Imperium and he was playing the Traitors; this may seem odd as Chaos is my army when I'm playing 40K, but Dave is a villain through and through and will rarely pick the good guys by choice. As it was the first time we'd given the game a run-through knowing all the rules to it (or at least that was the plan,) I figured we'd stick to the Brother vs Brother scenario for this. Turns out this was one of my better moves, because I still had to refer to the rulebook almost as often as if I'd picked up the game for the first time, only this time looking for the finer points of the rules I hadn't got a clue about and were by their very nature hard to find. Unfortunately for me, it was all downhill from there...
Apart from the coexistence battles, we were playing it cagey for the first couple of initiatives. I moved a few units including Jaghatai Khan and the Fabricator General into position to attack Angron on the next refresh phase, and brought a couple of tank legions on from the far West side of the board. Dave piled on the reinforcements for Mortarion, who was occupying Eternity Wall Spaceport with his Nurgle-infested units, and patiently waited for the refresh phase where the activation markers would disappear.
As soon as they did, Dave took the offensive. Using Vicillitudes of Chaos, I'd managed to divide a significant amount of Angron's forces, but Dave was undaunted by this and went straight for Jaghatai Khan. The fury of the Khornate forces plus the subsequent bombardment resulted in Khan being left out on his own, though Angron had 4 wound counters by the time they had finished. Dave then had a lucky draw of Order Cards and found two Drop Pod orders. He proceeded to slam down 5 units of Chaos Space Marines and a Thunderhawk right on top of the meagre forces that defended Lion's Gate Spaceport. As soon as the change of initiative phase kicked in, they found themselves in battle; the stacking rule wasn't going to save them since any coexistence fights take precedence, and obviously they never stood a chance. Worse, that very cleverly-timed move had landed Dave's initiative marker right on top of the Spaceport Victory square, and as by then he controlled all 4 spaceports, this effectively gave the game to him.
So, what would I do differently next time? Well, if luck were not a factor, I might consider moving some more units in defence of Lion's Gate Spaceport. Thinking about it, I've got a Titan and the Blood Angels in easy reach, plus Sanguinius, so moving an effective defence force there is not a problem and would certainly have caused Dave some problems achieving a Spaceport Victory. In of itself this is a good strategy anyway. Angron and Mortarion have control of 2 Spaceports at the beginning of the game, the other two depend on the results of the corruption draw and in this case Damocles would have to be abandoned but there's not much that could happen to Lion's Gate that you couldn't do anything about.