From Lexicanum

Steel Rain was a tactic that was dictated under the Codex Astartes which involved the use of drop pods deploying Space Marines anywhere on the battlefield. This provided less reliance on base defences and relied more on Battle Brothers being held in the ships above the planet which were ready to be deployed at a moment's notice; whether it was within enemy positions or within the small Space Marine base itself.

Brother Captain Indrick Boreale made use of this tactic in the Kaurava system.

Source

• Dawn of War: Soulstorm