Here is the full list of all 10 Chess Knights: Viking Lands achievements.
Free all your allies from the Viking Lands
Save the lost ones from Ymir's Glaciers
Save the lost ones from Yggdrasil Way
Save the lost ones from Midgard City
Save the lost ones from Njord's Bay
Rescue all your imprisoned allies
Rescue the arrested from the forest
Rescue the arrested from the village
Rescue the arrested from the docks
Start the assault