(GPO, Washington, July 1917) Liaison Instructions for All Arms, War Dept Document No. 625. 56 pages + folding plate at the back, Sm 8vo (5x8"), wrps, stapled. Cover states: "Translated from a French Manual of 1917 by the Army War College". Cover marked: SECRET AND CONFIDENTIAL/For official use only. Not to be taken into front line trenches". Extensive coverage of observation by aeroplanes and balloons. (Obviously the U.S. Air Service learned much from the French!) Good; usual toning and corner bumps.