Battlefield 1 (BF1) - All Field Manual Locations: Through Mud and Blood

There are a total of 66 field manuals to collect in Battlefield 1. There are 5 in each of the missions located within the War Stories. None of them are missable, and you can replay missions from the main menu in case you miss any. As soon as you pick one up, it saves. You don't need to go and pick it up again if you die, or get to a checkpoint before quitting. You will unlock the "Enough for a Library" trophy / achievement for collecting all 66 of them. There's a codex entry for each mission for finding all 5 within a mission, and those are also related to some trophies / achievements.

You can also check how many you have in each mission by hovering over a mission and looking at the little book symbol, if you don't have them all some will be greyed out. You can also check how many you have on in the pause menu.

This video goes over all of the field manuals found within the "Through Mud and Blood" war story. This consists of the following sub missions.

Timeline:

Over the top

[0:05] Field Manual #1
[0:45] Field Manual #2
[1:21] Field Manual #3
[1:54] Field Manual #4
[2:29] Field Manual #5

Fog of War

[2:59] Field Manual #6
[3:29] Field Manual #7
[4:09] Field Manual #8
[4:51] Field Manual #9
[5:31] Field Manual #10

Breakdown

[6:14] Field Manual #11
[6:51] Field Manual #12
[7:35] Field Manual #13
[8:50] Field Manual #14
[9:38] Field Manual #15

Steel on Steel

[10:41] Field Manual #16
[11:13] Field Manual #17
[12:27] Field Manual #18
[13:06] Field Manual #19
[14:08] Field Manual #20

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