midnight
At dark the prisoners disposed of themselves as well as they could for the night . Tom saw the captain go through all the forms of preparing for a comfortable lodging , and he did the same himself . For hours he lay ruminating upon his purpose . When it was midnight , he thought it was time for him to commence the enterprise . He worked himself along on the floor till he reached the principal entrance . The door was open , as it had been all day , to enable the guards to obtain an occasional view of the prisoners . The sentinels were evidently in no condition to discharge their duties with fidelity , for they had been marching and fighting for two or three days , and were nearly exhausted .