4. “Moonshine Sonata”

Source saw following secret instructions issued by Senior Signals Officer, Fliegerkorps 1 and dated 1400/9/11/40:

W/T data of KG 100 for “Moonlight Sonata”:

(1) Frequency of 4492 kcs. alternative 4730 kcs. KG 100: Ground Station’s call-sign F4G: Hptm. Aschenbrenner’s aircraft, F4 GA; other aircraft use F4G with letters B, C, D, etc. added.

Aircraft three-letter code LM 4, with following “Verfuegungssignale”:

No. 9 — KORN (sic).

No. 10 — Weather at English coast.

No. 11 — Weather at target.

No. 12 — Bombing conditions over the target.

No. 58 — Knickebein Beam 3.

No. 59 — Knickebein Beam 4.

No. 60 — Beam interference.

No. 61 — Beam very coarse broad.

No. 62 — Intersection of beam is over the target.

No. 63. — Beam is to left of target.

No. 64. — Beam is to right of target.

No. 15 — Target Area 1.

No. 16 — Target Area 2.

No. 17 — Target Area 3.

No. 18 — Target Area 4.

KG 100 will give the tuning-signal at 1300 hours on day of operation, to be repeated at 1315 hours by Airfleet 3, call sign D 3R.

(2) In case the attack is not to take place on account of the weather report from KG 100, instructions to this effect will be issued:

(a) By telephone via the Fliegerkorps (plural: but number of them unspecified).

(b) By W/T: the main W/T station of the C-in-C, German Air Force, will send the code group “MOND MOND” (i.e MOON MOON) three times. Airfleets 2 and 3 will repeat the group three times.

(3) Five minutes after the signal “MOND MOND” the Knickebein stations will be shifted on to alternative targets: duration of shift over about twenty minutes. Knickebein will continue to operate during the shift over.

(Reliability (A) except for paragraph 3, which is (B). Source assumes that “Moonlight Sonata” is a code name for a particular operation.

Intelligence

This is the full deciphered text of the signal that revealed "Moonlight Sonata" to the British.

It was broken at some point between 07.35 GMT on 10 November and 05.00 on the 11th and sent to recipients as teleprint No. 4 of that batch of intercepts.

Pencilled in the file copy's margin, alongside "No. 9 — KORN (sic)", is the note: "30/11 Aschenbrenner over Southampton: 1812 Korn 8 large fires, 1818 Korn 20 large fires"