"The Defence of Duffers Drift" is a fictional account of a young, inexperienced British officer, who is tasked with holding a river crossing with 50 troops against a larger enemy force. His initial failures and eventual victory serve as an entertaining and instructive vehicle to convey the principles of small unit tactics. Because it deals with principles, this definitive work has endured to this day and is still on some of the required reading lists of the U.S. Army and Marine Corps. (Goodreads)