Warhammer 40,000: Dawn of War/Walkthrough

Introduction
The Dawn of War campaign has 11 missions where you take control of Space Marines of the Blood Ravens chapter (and occasionally some auxiliary Imperial Guard troops) against Orks, Eldar and Chaos Space Marines. The campaign has three difficulty levels, of which Normal is actually rather easy, Hard is rather standard and Insane is rather hard.

General Tips & Tactics
There are some generic tactics and techniques that apply regardless of the mission or the specific units in play. On the other hand, some multiplayer fundamentals - such as build orders and early harassment/rushing - are of no consequence in campaign play.

Play The Tutorial
It may sound stupid, but you really should. The tutorial will teach you the basic gameplay mechanics, the role of your backbone units, and what you will need to get the different units/structures. This guide will not explain things that are already clearly described in the tutorial, such as Requisition, Power, Squad/Vehicle Cap, Strategic Points, reinforcing squads, et cetera.

Right Tool For The Job
Many units and weapons in Dawn of War have a specific role. Anti-vehicle weapons have good damage against vehicles but ineffective against infantry squads, and vice versa. Strong ranged combat units tend to be weak in close combat. You can't just build a bunch of units, select them all and send them to the enemy base; they will get slaughtered. You have to build your army according to what the opponent has, choose which units will be in front and which will flank or hang back, and you must see that your units choose targets they are effective against.

Tying Up
To prevent a strong ranged squad from using their most effective attack, send a squad - preferably a fast-moving melee specialist squad - to engage them in melee. They will be unable to fire, and probably lose to your melee squad anyway, although you want to pepper them with ranged units for good measure if possible. If the enemy squad is really hurting you and you don't have anything better, order one of your own ranged squads to charge and melee them.

Screening (Meatshielding)
To prevent an enemy melee squad from reaching your ranged units, you should have a melee squad of your own available to intercept. Then use your ranged units to help out the meatshield squad, otherwise it could lose or be severely weakened.

Dancing
If the enemy tries to melee your ranged squad and you cannot screen, move away the targeted squad while you shoot at the enemy with another squad. Run away until the enemy squad switches its target, then stop the dancing squad to fire upon the enemies while you run away with the other. Repeat until enemy is dead.

Disruption
Some attacks - like artillery fire or the melee attacks of certain units - knock infantry units down and send them flying all over. Even if the actual damage inflicted were minimal, this will prevent a squad from firing and render them quite useless. Use this to your advantage and don't keep your own infantry in a single big bunch.

Pause The Game
If you have trouble micromanaging your army fast enough or don't know what to do, remember you can always Pause and think for a minute.