Every Story Has an Ending
Sub Quests:
( To avoid long traveling times via ship, Fast Travel to a port near the island of Samos and call the Adrestia before accepting the first sub quest. Do the same, by traveling to a port near south of Athens, before accepting final sub quest.)
- Letter From Home
- Regrets
- Followers Of Truth
- Defense Of Samos
- Moving Forward
EDIT:
Some people are reporting that the final sub-quest 'Moving Forward' is not appearing and the achievement is therefore not popping. Thanks to Calex dEUS and other commenters who figured out that you need to complete a side quest in Athens, called 'We Remember' for the sub-quest 'Moving Forward' to trigger.