I picked up a copy of Tactica Imperialis on Saturday and I'm really enjoying it so far. It's sub-title is a History of the Later Imperial Crusades, and it purports to be a document for military historians and officers in training. There are four military campaigns outlined; so far I have read two.
The first is set on a mining colony which has been attacked by Dark Eldar. The miners are aided by Space Marines of the Iron Snakes Chapter in a most unorthodox fashion. The series of battles are recorded with the help of a map of the colony and some new and recycled artwork. I think this section is written by Dan Abnett, as I have heard some rumours about him writing a Space Marine novel about the Iron Snakes. It is well done and could easily be played out as a mini campaign - the forces involved are relatively small and characterful. Fluff junkies will enjoy the political struggles between the Colony Governor, the Governor Subsector and the Space Marines, as well as little nuggets of detail outlining colony charters and the enigmatic Dark Eldar.
The second campaign concerns Lyubov, a Hive world involved in the Sabbat Worlds crusade. Considering the subject matter I would again assume Dan Abnett wrote this section of the book. He is particularly good on the internal struggles within the Imperial forces - General Carnhide is given a mish mash of regiments and is expected to retake several hive spires. Each branch of the military forces (Guard, Navy, Mechanicus) fight to have their pet attack plan approved and Carnhide plays them off against each other to try and mount a cohesive assault. Things start to fall apart when the Blood Pact are encountered and Carhide realises the scale of his task. Some of the maps and art in this section are a bit ropey - there are three full page pictures of Titans for example, which I'm sure I've seen numerous times before. Still, it's yet more background for the Sabbat Worlds Crusade and the Gaunts Ghosts are nowhere to be seen.
At the time of writing I have two more campaigns to read, and as soon as I do I'll complete my review and post the full thing up on my website proper. In fact, it has inspired me to go back to my other background books and review them, so that I'll have the full range of campaign histories.