On leadership, the following manuals are very organised and written well even the prefaces by themselves are succinct and take into account organisational conditions that could similarly occur for an engineering-focused org.

The U.S. Army Leadership Field Manual FM22-10 (1951): https://www.bits.de/NRANEU/others/amd-us-archive/FM22-10%285...

The U.S. Army Leadership Field Manual FM22-100 (1999): https://www.armyheritage.org/wp-content/uploads/2020/08/FM-2...

On technical writing aimed at and for an engineering team, since our subject is engineering strategy. Similar to the manuals above, these are succinct and cover a lot of ground.

U.S Department of Army Engineer Troop Organizations and Operations (1965): https://ia802804.us.archive.org/13/items/FM5-11969/FM5-11969...

On technical writing, this is a medical manual thats detailed and limited in scope for good reason. Look through and you can that it primarily serves as reference with the assumption of limited yet enough competence to do any medical work.

U.S Army Special Forces Medical Handbook ST 31-91B (1982): https://ia800606.us.archive.org/18/items/milmanual-st-31-91b...

On documenting use case scenarios and instructions related to that specific scenario.

U.S War Department Technical Manual 6-Ton, 6x6 Truck TM9-813 (1944): https://ia600202.us.archive.org/25/items/TM9-813/TM9-813.pdf

Additional references to look through, courtesy of the Internet Archive:

U.S Military Manual Collection: https://archive.org/details/military-manuals

The Manual Library Collection: https://archive.org/details/manuals

Edit: formatting and one more resource:

Army OE Program: https://armyoe.com