Books in World War I (sorted alphabetically by author)
- Some War-time Lessons Frederick P. Keppel
- The Economic Consequences of the Peace John Maynard Keynes
- Battery E in France: 149th Field Artillery, Rainbow (42nd) Division Frederic Richard Kilner
- Tommy Atkins at War: As Told in His Own Letters James Alexander Kilpatrick
- The Diary of a U-boat Commander Sir Stephen King-Hall
- France at War: On the Frontier of Civilization Rudyard Kipling
- Company B, 307th Infantry Julius Klausner
- The Harwich Naval Forces: Their Part in the Great War E. F. Knight
- "Brother Bosch", an Airman's Escape from Germany Gerald Featherstone Knight
- "Over There" with the Australians R. Hugh Knyvett
- Four Weeks in the Trenches: The War Story of a Violinist Fritz Kreisler
- The Attack in Trench Warfare: Impressions and Reflections of a Company Commander André Laffargue
- The Backwash of War Ellen N. La Motte
- The Peace Negotiations: A Personal Narrative Robert Lansing
- Treat 'em Rough: Letters from Jack the Kaiser Killer Ring Lardner
- Men in War Andreas Latzko
- A Minstrel in France Sir Harry Lauder
- Foch the Man: A Life of the Supreme Commander of the Allied Armies Clara E. Laughlin
- Letters of Lt.-Col. George Brenton Laurie G. B. Laurie
- Fighting France Stéphane Lauzanne
- The Comrade in White William Harvey Leathem
- The Riddle of the Rhine: Chemical Strategy in Peace and War Victor Lefebure
- Dixmude: The epic of the French marines (October 17-November 10, 1914) Charles Le Goffic
- Letters of a Soldier, 1914-1915 Eugène Emmanuel Lemercier
- A Jewish Chaplain in France Lee J. Levinger