There is a lot crammed into the 105 pages of this PDF. D@W: Campaigns is a great supplement for people who want mass combat added into their game but still want it abstracted into in an evening of play.
ACKS books are well thought out, and there is a high level of interplay between all the moving pieces of the rules. D@W is no different. So much of the structure of D@W ties back into the ACKS rules about economics and domains. So when you get this, I would advise reading through it at least twice. Once to get a wide view of the Campaigns system and a second to dig deeply into each section. D@W provides cross-references to the other ACKS books where they apply, which is very helpful.
If you are looking for a rule set for a d20 game that abstracts mass combat in a fun, simple way, while still providing players influential choices, check out D@W. I wrote an in-depth review of Campaigns at: http://originsofadarkgod.wordpress.co-
[5 of 5 Stars!]