“We’ve got to stop this, it’s stupid.”
I completely agreed, but to stop it, I needed my whistle (well, Peyssou’s whistle), so I searched, perspiration running down my forehead, in all my pockets, without managing to find it. As I searched, I realized, even through all that anxiety, how ridiculous I was. The commander-in-chief could no longer command his troops, since he had mislaid his whistle.
I could have shouted out “Hold your fire!” Even Miette and Catie in the fort at the entrance would have heard me. But I did not do this: I do not know why, but at that moment it seemed very important to me that things be done according to regulations.
I finally found this precious talisman. There was nothing surprising; it was where I had left it, in my shirt pocket. I blew three short blasts, and these, when I repeated them a few seconds later, managed to silence our guns. Yet my whistle must have awakened some echo in the military soul of Vilmain, since, from the rampart I was crouched behind, I heard him screaming at his men, “What are you firing at, you bunch of cretins?”
On that, on both sides, silence replaced the outburst. To say deathly silence would be overstating the case, since no one had been shot. This first part of the combat ended in farce and immobility. We did not feel a need to leave Malevil in search of the enemy, and the enemy had no desire to come forward to meet our bullets, by moving into a breach of only four or five feet wide.
I did not see what happened next; it was the outside commando that recounted it to me. Hervé and Maurice were desperate. There had been a mistake in positioning the blockhouse. It allowed a clear view on people coming on the Malevil road if they were upright. But as soon as they lay down (and they did), they were invisible: the grassy ridge of the path hid them completely.
Because of this, Hervé and Maurice could not shoot. What was more, even supposing an enemy were to stand up, they did not know if they should shoot or not, since Colin’s gun remained silent.
 Capital letters (two of them) are possible but not obligatory.
 In the breast pocket of my shirt : but then again, where else do shirts have pockets ? Still, if you knew the expression « breast pocket » it is no doubt best to use it.
 As often, this reminds me of a popular song (from the 1940s). « I blew a little blast on my whistle » by George Formby Senior. You can listen to it here : https://www.youtube.com/watch?v=aeXMexIAroo
 If you were tempted by any translation other than « must have », you must urgently read again the modal verbs section of your Grammaire Explicative de l’Anglais.
 Jerks, bloody idiots, etc.
 I’m fairly confident that, strictly speaking, « deathly » is correct (resembling death) and « deadly » is not (liable to cause death). However the British national coprus shows that people do use both.