Tirpitz on the loose

[tameraire01]

Convoy PQ17 leaves iceland and heads for the soviet union, Now what if Tirpitz under the cover of darkness on a moonless night slips her moorings and heads north, What in the RN and USN arsenal could stop her?

[dunmunro]

Convoy PQ17 leaves iceland and heads for the soviet union, Now what if Tirpitz under the cover of darkness on a moonless night slips her moorings and heads north, What in the RN and USN arsenal could stop her?

PQ-17 had a distant escort of cruisers and battleships:

http://en.wikipedia.org/wiki/Order_of_b ... nvoy_PQ_17

[tameraire01]

Convoy PQ17 leaves iceland and heads for the soviet union, Now what if Tirpitz under the cover of darkness on a moonless night slips her moorings and heads north, What in the RN and USN arsenal could stop her?

PQ-17 had a distant escort of cruisers and battleships:

http://en.wikipedia.org/wiki/Order_of_b ... nvoy_PQ_17

which got pulled off leaving them to be picked off by the Germans.

[Dave Saxton]

Convoy PQ17 leaves iceland and heads for the soviet union, Now what if Tirpitz under the cover of darkness on a moonless night slips her moorings and heads north, What in the RN and USN arsenal could stop her?

Of course in the Artic in July there is no night. It is daylight 24/7. Conversely in the winter it is night 24/7 from roughly the last week in Nov to the last week in Jan. It changes rapidly to and from equinox though. By March 21 it is 12/12. When TP bombarded Spitzbergen there was 14 hours between twilight and it wasn't very dark during the twilight periods. Visibility was 20 miles.

In the tropics it's very different. When I was in Honolulu the sun came up at 4:30 am and set at 8:00 pm almost all the time. There is very short twilight periods in the tropics. It can be, and usually is, pitch dark 15 minutes after sunset.

The problem for the Germans throughout the war was that their communications were not that secure. Even the Kriegsmarine communications that were secure were usually compromised by sloppy Luftwaffe communications. And the land lines going to and from Norway had been tapped by the Sweeds who gave it to the British.

British RN and merchant marine communications were also not secure to B-dienst, so it was open book with both sides knowing what the other side was up to in general terms from their comms.

[tameraire01]

if she did venture north instead of being in Norway as a target for the RAF/USAAF and FAA until wars end. What sort of damage could she do and how would we stop her.

[Dave Saxton]

The best counter during summer is aircraft carriers.

[tameraire01]

Would we send Implacable and her sister along with KGV to stop her?

[tommy303]

During the summer months, certainly CAP provided by carriers would be necessary for any task force attempting to intercept Tirpitz because of possible attack by the Luftwaffe which could operate almost around the clock that far north.

[aurora]

As further protection, the convoy was to be tracked at about 200 mi (320 km) by Home Fleet battleships.The second, heavy covering force, under the command of Admiral John Tovey, was made up of the British aircraft carrier Victorious, battleship Duke of York (flagship), cruisers Cumberland and Nigeria, the American battleship USS Washington, and nine destroyers.
As Tirpitz would undoubtedly have been picked up via Ultra -Victorious would have flown a strike off to counter the danger;with HF making all speed to intercept.

[Dave Saxton]

As Tirpitz would undoubtedly have been picked up via Ultra

Ultra was not effective in deciphering Naval Enigma during 1942. From the 1st of Feb 1942 the KM began to use the Enigma machines with an extra rotar and new key nets. They changed the codes. The black out extended to mid Dec 1942, when Ultra began to break into the U-boat key nets from cribs of the short weather cipher Enigma key net, and from the short signal procedures used by U-boats from Feb 1943. The Enigma key net that would have been used by Tirpitz or Scharnhorst..ect.. during war operations remained mostly unreadable on any given day to the end.

From mid 1941 to Oct 1941 Naval Enigma was broke into because the keys had been captured from weather ships, and from U-110. This allowed the rounding up of the supply ships and tankers. But those Enigma keys expired at the end of Sept 1941 and the Naval Enigma de-ciphers became hit and mostly miss until the complete black out of 1942.

Ultra could have infered some things from traffic analysis, or from Luftwaffe Engima intercepts, and dock yard ciphers (non Enigma) intercepts at the time of PQ17. Additionally, the Swedish intelligence services had tapped the telephone lines between Germany and Norway and they shared this information with British Intel with some delay.

The RN operated their battle groups at some distance from the convoys they covered to prevent major warships from being sunk by U-boats and torpedo bombers. We now know that Tirpitz could have fallen on PQ17 without running much risk. Once the convoy had scattered the Germans decided that Tirpitz should run no risk at all, however.

[aurora]

Dave-I am quite astonished to learn that there was an Ultra "blackout" until Dec.1942.
but I was remiss in using the term "picked up"
I quote from David Irving's "Convoy PQ17":-
"Only now did a fresh Ultra-intercept belatedly arrive in Commander Denning's room: the order of Admiral Commanding Arctic of 11.30 am that morning to the Uboat Group Ice Devil.It said -No own naval forces in operational area at present,but is the major target for Uboats when encountered.Boats in contact with convoy are to keep at it----
Commander Denning was horrified-this confirmed his gut feeling that the German Battle Fleet was NOT at sea.But the damage was done; the signal had been sent by Pound-"Convoy to Scatter"
Irving did not imagine these Ultra intercepts at that time -Correlli Barnett and Steven Roskill accounts confirm that Ultra was active at the time of Convoy PQ17.

I do not however believe that Tirpitz would have sortied in the circumstances described above; but the premise being a "what if" situation-I suppose anything imaginable could have occurred-including the sinking of the cruiser squadron IF they had stayed on.Please correct me if I am wrong

[Dave Saxton]

Interesting. What key net was that on assuming it was Engima? Is it from Naval Engima or something else? For example, if the Luftwaffe was also intended to read the message, it would have been sent on the Luftwaffe key net using only 3 rotors. Not all messages were using Enigma and there were several different versions of Enigma. Interesting that no Ultra intercepts between Tirpitz and other surface German units or between Tirpitz and Kiel are mentioned.

[Dave Saxton]

If Battle Group Tirpitz was not recalled, then its possibile that Tovey with the KGV and Washington could have tried to intercept Tirpitz on the way back. (they could not get there in time before Tirpitz attacked.) However, they would have been running an extreme risk to the Allied battleships of Luftwaffe torpedo bomber attack. Remember Force Z's fate. Tirpitz would have enjoyed Luftwaffe air cover throughout.

[aurora]

Interesting. What key net was that on assuming it was Engima? Is it from Naval Engima or something else? For example, if the Luftwaffe was also intended to read the message, it would have been sent on the Luftwaffe key net using only 3 rotors. Not all messages were using Enigma and there were several different versions of Enigma. Interesting that no Ultra intercepts between Tirpitz and other surface German units or between Tirpitz and Kiel are mentioned.

What Hitler did not know and Raedar refused to believe possible,was that the British had developed a top secret computer capable of cracking the Schlissel-M-the machine ciphers used by the German Navy-KM-rapidity had varied from day to day but had been crippling for the Germans.These decoded messages stamped with the special Ultra secret classification had led the British Battle Fleet to the Bismarck in May 1941-it was this device that tipped off the Admiralty that Tirpitz had arrived in Norway along with the rest of the entourage PE,AS plus destroyers.It was Ultra that enabled the Admiralty to station a submarine in Trondheim approaches

[aurora]

If Battle Group Tirpitz was not recalled, then its possibile that Tovey with the KGV and Washington could have tried to intercept Tirpitz on the way back. (they could not get there in time before Tirpitz attacked.) However, they would have been running an extreme risk to the Allied battleships of Luftwaffe torpedo bomber attack. Remember Force Z's fate. Tirpitz would have enjoyed Luftwaffe air cover throughout.

Adm Tovey in KGV, also had air support in the shape of HMS Victorious,USS Washington and Wichita, Hamilton's Cruiser Squadron together with Broome's destroyers; and it is just possible we had another Bismarck situation to deal with if they stayed to battle.Yes I do remember Force Z's fate, but maybe,just maybe,fortune may have smiled on our efforts again.Quite a melee!!