Dawn of War – Winter Assault is the first expansion for Dawn of War. It was developed by Relic Entertainment and released by THQ on September 23, 2006.
Winter Assault contains two new single-player campaigns, one for Order and one for Disorder. Each campaign has five missions with two alternatives for the final one, meaning a total of 14 if all options are explored by the player.
The campaign missions in Winter Assault are markedly more challenging than the original Dawn of War missions, requiring the player to cope with limited units, time limits, or overwhelming enemy waves.
- New factions: Adeptus Mechanicus and Steel Legion
- Unit upgrades limited
- Chaplain for Space Marines
- Mega Armored Nobz for Orks
- Fire Dragon Squad for Eldar
- Khorne Berserkers for Chaos
- Lictor for Tyranids
- Chimera Assault Tank for Imperial Guard
- Overseer for Necrons
- Greater Knarloc for Tau Empire
- Exorcist for Sisters of Battle
- Reaver Jetbike for Dark Eldar
Reviews for Winter Assault were generally positive, with a 85% rating from Metacritic. No major flaws or issues were complained of, and some reviews considered it one of the best RTS games ever.
- Metacritic: 85% 
- Gamespot: 8.3/10 
- Gamespy: 4.5/5 
- IGN: 8.5/10 
- 1UP.com: A  and B+ 
- The expansion was also published in an alternative box that mentions the "Game of the Year" title won by Dawn of War
- The Gold Edition bundled Winter Assault together with the original Dawn of War (March 31, 2008)
- The Platinum Edition added Dark Crusade to the bundle in November 2010
- Dawn of War: Anthology was the Platinum Edition in a different box, relesed in 2010
- Dawn of War: The Complete Collection added the final expansion, Soulstorm, in March 2012