In message , Biz WDØHCO
writes

Snip

I'll also mention code breaking in the anti-sub war.

hmmm ok - where should I start?

We are of course talking about the British breaking the codes being sent and
received by German Enigma Code machines. Brits are proud of saying their
collection of eccentric mathematics wizards and puzzle solving misfits broke
the code in something like 3 or 4 weeks.

I haven't. Some messages were never broken. Some were read immediately.

What is glossed over is that the front line German Radio OPs were somewhat
lazy and seldom if ever changed the code wheels on the machine. The German
high command believed their code machine unbreakable but even so still
changed the code wheels on a weekly basis for high level comms.

Any decent book on code-breaking will relate this point. I've never
known it being 'glossed-over'. Most of the breaking depended on
mistakes, or duplication, or repeats of messages without changing the
wheel positions.

The Luftwaffe was very lax on this point, using the same start position
for several messages.


They believed even if front line comms could be broken - they were of little
strategic value to the enemy. Of course we now know, if you broken low level
comms you can follow the messages up the chain and stand a good chance of
breaking that code if you know what is in the message being sent.

The Bits did this and now had access to most of the Germany Armed Forces
comms.

Now what to do with it?

What now follows is my own speculation - much of the story still remains
classified to this day. I can only go back and look at the historical facts
and come up with some fairly logical deductions -

..in other words - I'm guessing...

(1) Clearly - Churchill could have told the Americans early on - He choose
not to do this until much later.

I haven't got the question so can't comment on this point.

(2) Britan could not directly go after subs and ships. To do so would tip
the Germans that the code was broken and force them to change their wheels
on a daily (or hourly) basis. Remember it took 3 weeks (and I suspect much
more) to break each code. So even though they had a stolen Enigma and the
tools to break the code - it would have been of little use if the code was
changed daily.

The code was changed by the Kreigsmarine daily, sometimes every three
hours.

(3) America at the time was isolationist. The Brits saw what a single Jap
Attack at Pearl Harbor had done. Almost overnight, America was at war - with
Japan. Most Americans wanted to fight the Japs only - they had no beef with
Germany.

(4) The Lend-Lease convoys were US Merchant Ships carrying U.S. War Material
protected by the U.S. Navy Ships manned by US Sailors.

Err... Some were. The US government's policy was even-handed. Pay for it
and collect it. Most convoy ships were European at the start. Only
later, after 11th Dec 41, and when the US started building Liberty ships
in huge quantities, did the ratio change.
The US and Canadian Navy escorted the convoys eastwards to about
half-way when they handed over to the RN.
Before 11th Dec '41 the USN provided some escort vessels, ie 'Reuben
James', which on occassion did engage the U-boats.

The Brits knew the
exact locations of German subs out to sink the convoys but kept quiet.

Rubbish. We wouldn't have lost a single ship if that was so. I can
remember the 9.00 BBC news, each evening, starting "The Admiralty
regrets to announce the loss of the following ships...." then followed a
list of from 2 to 20 ships. It was harrowing.

The
loss of some shipping and American lives would keep the United States
focused and involved with the war in Europe.

Bollox.

(5) As you can imagine - the Americans were livid when finally told. Not so
much for the loss of American life but for the fact they were so well played
by Churchill.

If only.

(6) This and the massive defeat ("Heroic Retreat" as the Brits tell it) at
Dunkirk were probably the two major factors in selecting an American as
Supreme Allied Commander.

Our 'Heroic Defeat' matches your Philipines, I suppose. The RAF lost
200+ fighters defending Dunkirk.


Eisenhower for the invasion and afterwards. Which involved at least 60%
Brit and Commonwealth troops on the first day.


Of course all this is just idle speculation...

You should have put that in capitals , and underlined it.

I think the code breaking used in the anti-sub effort came much later when
it was certain America would join the British War effort.

Do you think we wouldn't have done it to save our own ships?

But we may never really know. -B

We know a lot more than you have written.

Mike
--
M.J.Powell