Codex entry challenges are a new type of collectible in Battlefield 1. Instead of finding and collecting an item, like field manuals, codex entries require you to complete challenges. Some codex entries are easily unlocked by completing required mission objectives, while others are more challenging.
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Why should I collect codex entries?
Unlock codex entries to gain access to logs that provide additional insight into the events of WWI. These codex entries will also unlock new multiplayer modifications.
How many codex entries are there?
The campaign in Battlefield 1 has 52 codex entry challenges. Unlock all 52 to earn the Master of Adaptation achievement.
How do I know what codex entry challenges I need to complete?
Pausing the campaign will bring up a screen that lists all the codex entry challenges in the chapter.
How do I know when I've unlocked a codex entry, and how do I track my progress?
You will receive an on-screen prompt when you've unlocked a codex entry. You can check your progress through the campaign tab of the main menu. Toggling to a specific war story will allow you to see your progress in individual chapters.