Ok, heres how it all started and how it works. It started out a role call just to see how many people we had, but hten as the list got larger we started groupin ghtem togethor just for fluff and then we put them into actualy units with hierarchy and such. There were I think 2 or 3 complete armies at one time, each made up of several (usually 7+) corps each made up of several (usually 3+) divisions each made up of between 4-7 regiments, each regiment being the army of an actual player. Heres an example:
1st Cadian Corps, 6th Shock Army
>>>>1st Division-
+++2nd Cadian (Black Watch Royal Highland Regiment of Cadia)+++
+++Lieutenant-General Sir Arthur Currie+++
5th Cadian
6th Cadian
7th Cadian (2nd Company)
13th Cadian
19th Cadian
273d Cadian
>>>>2nd Division-
17th Cadian
20th Cadian
***24th Cadian "White Knuckles'
***Brevet-Major General Vellas Helsher
27th Cadian
31st Cadian
52nd Cadian
118th Cadian
>>>>3rd Division-
65th Cadian
75th Cadian
>>>Colonel Trigarius
99th Cadian
>>>Colonel Townsend
140th Cadian
***148th Cadian
***Capt. Lindgren
>>>>4th Division
102nd Cadian Legion
231st Cadian
1000th Cadian
Comagran Mutli-Role 1st Regiment
***9th Flynn Defense Detachment
***Colonel VanValk
57th Anurian
>>>>5th Division (Space Marines)
The Red Unicorns
***Hanz Gredariens Templars
>>>6th Division (Eldar)
***Warriors of Altaioc
Those without names are just because their players either didnt have names for their commanders of they went AWOL or MIA before I could get them. Those with the *'s beside them were them divisional commanders. And the one with the +'s surrounding it (thats me) is the Corp commander, and being the commander of the 1st corps in the army, the leader of the army. What this did was establish a chain of command. This is the 1st Cadian Corps, 6th shock army. The Leaders of each army would meet, along with the Warmaster (the position given to the fellow who organized this all, there were after all several thousand regiments when it started) and discuss and plan an attack (it originally started out as we just each selected a sector and defended it, but that didnt work to well). Then once a decision had been reach, the Generals would send an e-mail to each of the corps commanders telling them the plans, the corps commanders wound then in turn, relay each divisions target tot he divisional commander, who would in turn relay it to each of his regiments.
We even had a reserve corps on standby for when sectors would be on the ropes, suffice to say they have been deployed in the Cadian Sector for the majority of the Campaign, they put up a steadfast defense on Saint Josemanes in its last day and were crucial in the reclamation of vigilatum.
What this system did (besides just being really cool for the fluff purposes) was allow us to force Chaos to react to us, instead of vice versa. We chose what planets that they would have to post their battles on to prevent losing them, instead of the other way around. Having such a large number of people focusing their battle on a single sector, system or planet usually pushes the target up over one of its "bump" levels, these levels being 20, 40, 60 and 80 Imperial control. When a target goes over its "bump" level, every other planet or system in that system or sector goes up 5%, however, if a target fall below a bump level, then they all go down 5%. So this allows us to control the bump levels quite well. Also, gamesworkshop has stated that it is not just the number of battles won (although this certain does matter quite a lot), but the number of battles won in a time period, so we may have more wins than the Forces of disorder on a planet, but if they post more wins than us in a single day, the planets control drops and vice versa.
That is what makes this so effective. On another note, you may notice the large proportion of Guard compared to, well everything else. Thats because this started out as a Guard Idea, all of the original members were guard but in order to increase the damage we could do to Chaos other armies are now being included, although they already have similar organizations made for their specific armies.
PS sorry for the length, and I hope I spelled vice versa right.