Blitzkrieg (German, "lightning war") is "a headline word applied retrospectively to describe a military doctrine of an all-mechanized force concentrating its attack on a small section of the enemy front then, once the latter is pierced, proceeding without regard to its flank."
The same can be said about using this Doctrine in Company of Heroes. The Blitzkrieg doctrine is a popular all-round choice and is especially effective against a British opponent. Using this doctrine means you can carry out fast assault ops by deploying overwhelming forces (with sneak attacks). Strong assault infantry and production bonuses help promote a strategy of aggressive expansion.