midnight
The saw was a very narrow one and , when they had made a hole with the augur , they found no difficulty in cutting the wood ; therefore they thought it was well to leave that for the last thing , and so betook themselves to their files , and soon removed enough of the bars to enable a man to crawl through . Then they returned to the door , and had cut round the lock , and made holes through which they could pass their hands to draw back the bolts , a short time before the clock struck twelve . Then they went to the window , and listened . They heard the bells strike midnight , and then a stir below , as the sentries were relieved . Waiting for a few minutes , until all had become quiet again , they drew back the bolts , took off their shoes , and went noiselessly down the stairs . The night was very dark and , although they could hear the tread of the sentries in the courtyard , they could not make out their figures . They crossed the yard , keeping as far as possible from the sentries .