Something we need to avoid from the first event is the long, real-life time span it took to complete. To that end, I've created a small system to try and avoid that problem.
For the coming weeks, the event will be divided into blocks of time two days long in-game. During these blocks, the PCs are free to act as they choose, provided that a) they choose a general goal to pursue in the block (scouting, searching, diplomacy...be more specific than this), and b) work toward that goal in some way. So you can't scout the horde and try to parley with it at the same time. This is primarily to limit the GM workload...also known as my workload.
That said, you are free to act within that context. You can do whatever you'd like in the general goal (even stupid things...but I don't know why you would, really). You are also free to act however you'd like and how often you'd like up until your goal is achieved.
Each in-game two day period will take a week. If you want to get more done, you'll have to be more active. So if you want to play out a conversation with a chieftain, you'll have to post more than once that week; otherwise, the GM (me or someone else) will automatically play out the results without your influence. Of course, not everyone can be that active. In that event, it's also perfectly okay to come up with general orders. However, the more active you are, the more you can get done and the more successful you will be, so do your best.
I know it sounds a little mechanical, but it can get boring if the event drags on simply because it must. And I'm not constraining your actions, just limiting the time you can take to complete them. Hopefully I'll be able to post quickly (and I'm sure there's a GM or two to help, as well), so let's give this a shot.
I'll write up your entries into the city tomorrow (the 29th) and we can consider the event begun. Just brainstorm for now and look forward to tomorrow.
Feel free to ask questions.