The Skjaldborg or shield-wall was commonly used tactic developed in Antiquity and implemented in many parts of Northern Europe, such as England and Scandinavia well into the Renaissance. The shield-wall did not require any great skill, and was essentially a shoving match with shields & weapons. This allowed poorly trained Fyrd (militia composed of farmers and other lower-class folk) to compete effectively with Huscarls, Thegns, and Hirdmen who were seasoned warriors that carried heavier weapons and consistently wore armor.
Below is a fearsome Skjaldborg of Gripping Beast Plastic Vikings. I feel these are the superior plastic vikings currently available. The casts are sharp with well defined features.
I totally dig them.
Now being a sneaky bastard, I often base plastics with neodymium magnets on metal bases . This allows flexibility for not only using a variety of basing conventions, but also allows one to slightly adjust miniatures when building a shield wall or positioning them in large base to base formations.