Another report by Ia, refers to intensified measures in naval and air warfare in connection with “Fall Gelb”.
“In consequence of this Directive, the Navy will authorize, simultaneously with the general intensification of the war, the sinking by U-boats, without any warning, of all ships in those waters near the enemy coasts in which mines can be employed. In this case, for external consumption, pretence should be made that mines are being used. The behaviour of, and use of weapons by, U-boats should be adapted to this purpose.” (C-21)
A third extract from the Naval War Diary, dated 6 January 1940, states:
“* * * the Fuehrer has in principle agreed (see minutes of report of C. in C. Navy of 30 December) to authorize firing without warning whilst maintaining the pretence of mine hits in certain parts of the American blockaded zone.” (C-21)
Whereupon, the order is given to Flag Officer, Submarines, carrying out that decision (C-21).
The report for 18 January 1940 states:
“The High Command of the Armed Forces has issued the following Directive dated 17th of January, cancelling the previous order concerning intensified measures of warfare against merchantmen.
“The Navy will authorize, with immediate effect, the sinking without warning by U-Boats of all ships in those waters near the enemy coasts in which the use of mines can be pretended. U-Boats must adapt their behavior and employment of weapons to the pretence, which is to be maintained in these cases, that the hits were caused by mines. Ships of the United States, Italy, Japan and Russia are exempted from these attacks.” (C-21)
An extract from the BDU War Diary (Doenitz’s War Diary) dated 18 July 1941, reveals a further extension of the above order so as to cut down the protected categories:
“Supplementary to the order forbidding, for the time being, attacks on U. S. warships and merchant vessels in the operational area of the North Atlantic, the Fuehrer has ordered the following: