
M.Dv No. 906 - Geheim! Handbuch für U-Bootskommandanten - Secret! Handbook for the U-Boat Commanders. From 1942, this secret classified manual is a bit off the normal path for me, but I thought it would be an interesting manual, and it certainly proved to be that way. When to surface, when to dive, when to stay up or down, periscope use, posting lookouts, how to deal with approaching aircraft, weather conditions, attack techniques, evasion techniques, lots of very interesting details about what to do as the commander of a U-Boat.
This manual was originally about 100 pages with wide margins, slightly reformatted and with lesser margins to make it 79 pages.
All text, no illustrations. A very unique look at the U-Boat world.