Office of the Chief of Naval Operations to Atlantic Coast Naval District Commandants
June 6th, 1918.
COMMANDANTS FIRST TO EIGTH NAVAL DISTRICTS INCLUSIVE
COMMANDANT FIFTEENTH NAVAL DISTRICT
BOX: Attention is especially invited to the delayed action of German mines as a counter to sweeping operations comma in connection with sweeping of channels period It is no guarantee that a channel is clear after having been swept the preceding day period The amount of delay in mines over three days is not known but it is possible that the mine may be set for a long delay period Continuous sweeping especially before large convoys sail is the best guarantee of safety COMMANDANTS FIRST TO EIGTH NAVAL DISTRICTS INCLUSIVE COMMANDANT FIFTEENTH NAVAL DISTRICTS 14006.
Source Note: Cy, DNA, RG45, Entry 517B. Document reference: “OP-26-H OP-3490.”