Oh, that word _liaison_! That linking up of the units of the attack in proper coördination! Is there any man of the combat divisions who does not know its meaning or who wants to hear it again? It never came into slang at home in the same way as camouflage; but it is a thousand times more suggestive of the actualities of war. _Liaison_ between the French and the American armies, between corps, divisions, brigades, regiments, battalions, companies, platoons, squads, and individual soldiers. _Liaison_ between infantry and artillery and trench mortars and planes and tanks! If you did not have it, why, the adjoining commander might be as much to blame as you, at least, and you could say that he was altogether to blame. It may be said that the history of the war will be written in terms of positions taken, and of positions which were not taken because coöperating units failed to keep their _liaison_. They were not up. When I mention that there were difficulties of _liaison_ in writing of any division, I am not saying who was at fault, as no one person was, perhaps, more than another. Other generals might be promoted and demoted, but General _Liaison_ remained the supreme tactician. "Establishing _liaison_" was fraught with more heartaches and brain-aches than any other military detail. Men prowled through the night in gas-masks under sniping rifle and machine-gun fire and artillery fire, to ascertain if the unit supposed to be on their flank was there: perhaps to receive a greeting from an officer hugging a fox-hole, "Why aren't you fellows keeping up with us?" _Liaison_ was most difficult in woods, though the fighting was not necessarily always the severest there. Men naturally took to the paths instantly they advanced into woods, and these, if they were not stopped by machine-gun fire, advanced ahead of those in the deep underbrush. A stretch of unseen wire might arrest a part of the line, without the men in _liaison_ on the right and left, as they plunged through the thickets, knowing that it had been stopped. The sheer business of keeping any kind of formation was distracting enough, without the sudden bursts of machine-gun fire, which might be so powerful that there was nothing to do except to take cover and consider a plan for silencing or capturing the gun. Unless the casualties were so serious that it was suicidal not to halt and mark out a plan for capturing the nest, and as advancing was a sure way of locating machine-guns and a prompt way of overwhelming them, we swept on in the spirit of our instructions and impatience. Captured machine-guns littered the paths of our battalions, in tribute to the effect of our impetuous rush upon gunners who continued to forget their orders to stand to the death when they saw the tidal wave of our soldiers about to swamp them.