Choosing high-explosive or armour-piercing shells against raiders

Would battlecruisers need armour-piercing shells to stop commerce raiders?

Not usually: high explosive could devastate lightly protected raiders, though armour-piercing would be useful against a tougher ship such as Admiral Graf Spee.

Many surface raiders were cruisers or converted merchant ships without protection that demanded heavy armour penetration. Large-calibre high-explosive shells could wreck the bridge and other unarmoured structures, disable weapons, and leave the target burning. Admiral Graf Spee is the caveat: armour-piercing shells would help against a more heavily protected raider, even if high explosive could still inflict serious topside damage. Shell choice therefore follows target construction instead of one rule for every commerce-war interception.