four o'clock
I agreed , with the reservation that I must always be on guard for the dawn-watch . I did n't explain why I was so anxious to take that particular watch , and , though I noticed Moira looking curiously at me , she made no remark . I knew from experience that men are at their sleepiest about four o'clock in the morning , and an attack can be successfully launched then that would fail at any other hour of the day or night . I had yet to test Cumshaw on active service , so I claimed the four o'clock stretch for my own . It does n't hurt to be careful ; I 've never yet met anyone who was sorry he had taken precautions . We camped within a hundred yards of the creek , and after supper Cumshaw and I sprawled on the grass and talked . Moira had retired to an improvised tent we had fashioned for her , and , as it was just out of earshot , we were free to speak our thoughts .