Such was the game of bluff which took place daily on that little stretch between the doors of Kaserne B for nine long months. Had any of the party been ever recognised and identified, the game would have been up; any ground for suspicion on the part of the Germans must have led either to the tunnel being discovered or at least the door being kept so closely under surveillance that another plan of getting underground would have had to be devised. But such a contretemps did not occur until three-quarters of the work had been done, seven and a half months from the beginning of it! And even then the mischief was not fatal to the success of the scheme. Luck indeed, but perhaps not quite so much a matter of mere luck as might appear at first sight. In the first place, there was the irrefutable law of mathematical probabilities. There were two platoons of Landstürmers detailed for the guard of the camp, and these relieved each other every 24 hours. Each platoon was divided into three relays of about ten men each, who did two hours on and four hours off. The allocation of “beats” varied for each individual sentry every time he went on duty. It might quite likely be a fortnight before the same man occupied the same station opposite the orderlies’ door. Add to this the fact that there were 550 British officers and over 100 orderlies in the camp; that the personnel of both the _Wachshaft_ and the prisoners was continually changing; and that the thoughts of any sentry at this period were more likely to be occupied with memories of meals in the past, with dreams of meals in the future, with the rottenness of the war in general and of Niemeyer in particular, than with the comings and goings and physiognomies of any British prisoners-of-war; and the conclusion is arrived at that the risk of detection on this account alone was, when all was said and done, comparatively slight.