Pingu
Credo
It's also why 2 handed axes were popular. They could pull apart the shield wall, hook over the top or stick in the shield.
daneaxes dont really work in a shieldwall. thy need a fair bit of space to be effective. but they are scary as fuck to fight against when someone who knows what they are doing is weilding one
a shieldwall is a place for stabby weapons. shortswords and spears