From what I read in the Iron Arms blurp, what came to my mind were the Spartans Phalanx and the Roman Phalanx. Like I can see a massive formation of Andurunan soldiers standing shoulder to shoulder with their shields locked together where the Andurunans in front will have their spears poking out from the side ready to thrust at the charging enemy, while the next row of Andurunans behind the front with their spears coming over the shoulders of the ones in front of them. And the rest act as the anchor to the ones in the front rows.

And all the Andurunans would do is let the enemy charge into the immovable wall of shields and spears before advancing once their momentum was broken on their shields.