"At midnight on 7 August all traffic entering and leaving the harbour was placed under strict naval control with the inauguration of an examination service under Captain Pasco's port defense organisation, to guard against surprise attack by disguised armed merchant ship raiders. No incoming ship could approach beyond the line between Flat Point and Cranberry Head without first establishing its identity to a naval examination vessel. Because no steamer was available this had to be performed by motor launches. The examination personnel, if satisfied, would order the gate of the submarine net to be opened. Vessels wishing to leave port would have to notify the examination one day in advance and receive, confidentially, a time when the gate would be briefly opened. Vessels could not enter or leave during darkness or when the weather was thick. One of primary responsibilities of the coastal batteries at Cranberry Head and Fort Petrie was to be ready at all times to open fire, first with warning shots and then for effect, on instructions from the examination staff... (vessels ) could pass, in or out, without displaying certain prearranged signals, set from day to day by the naval authorities."〔Tennyson and Flynn (2000) (Page 142 )〕