“Watches of night ” means
Watches of night : The Jews, like the Greeks and Romans, divided the night into military watches instead of hours, each watch representing the period for which sentinels or pickets remained on duty. The proper Jewish reckoning recognized only three such watches, entitled the first or "beginning of the watches," (Lamentations 2:19) the middle watch, (Judges 7:19) and the morning watch. (Exodus 14:24; 1 Samuel 11:11) These would last respectively from sunset to 10 P.M.; from 10 P.M. to 2 A.M.; and from 2 A.M. to sunrise. After the establishment of the Roman supremacy, the number of watches was increased to four, which were described either according to their numerical order, as in the case of the "fourth watch," (Matthew 14:25) or by the terms "even," "midnight," "cock-crowing" and "morning." (Mark 13:35) These terminated respectively at 9 P.M., midnight, 3 A.M. and 6 A.M.