The fictional discussion separates stopping an advance from defeating it. A defensively organized force may hold against Hive Fleet Leviathan, while driving it back requires mobility and sustained offensive action. The White Scars combine staying power with the movement needed to prosecute such a campaign. The setting is fictional, but the distinction applies to the real problem of matching force design to operational purpose.
Notable Point · 1:22:40-1:23:25
Stopping an enemy is different from driving it back
A Warhammer scenario distinguishes a force built to halt an attack from one able to manoeuvre, prosecute the campaign, and push the enemy back.