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Italian Subs in op Drumbeat

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  • Italian Subs in op Drumbeat

    As I understand it the four Italian Cagni class boats, completed in 1941 were wasted in transport duties. How could they have done if deployed on the US coast as part of the KM offensive there after the US DoW?
    1700t, with 10700nm range, they packed 36 torpedoes. Would this have been possible in technical and political terms, and would they have caused as much damage as their raw specifications suggest?

  • #2
    Could they get out of the Med / past Gibralter? Getting in was easy as the current pulls 5+ knots into the Med. Getting out is difficult unless you are surfaced....

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    • #3
      Short answer is yes. There were the minefields as well, but Italian subs managed. A equally large problem earlier was the Germans thought supporting the Italian subs at their bases in France a waste of effort. I'm unsure why. There were some central Atlantic patrols by Italian subs.

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      • #4
        Originally posted by Carl Schwamberg View Post
        Short answer is yes. There were the minefields as well, but Italian subs managed. A equally large problem earlier was the Germans thought supporting the Italian subs at their bases in France a waste of effort. I'm unsure why. There were some central Atlantic patrols by Italian subs.
        Italian subs tended to be poorly made and not up to the same combat quality of their German cousins. Their crew's training, aptitude and commerce raiding doctrine was not up to German standards either. Doenitz quickly learned this and usually sent them from their base at Bordeux, France to make less dangerous patrols to the South Atlantic where British ASW craft were fewer and less effective. Had they been used in Operation Drumbeat, they would have undoubtedly suffered serious losses from even the neophyte US Navy anti submarine operations off the US coast. Later, the Italian submarines returned to the Mediterranean where they suffered losses of over 2/3rds of their total number to British and US anti submarine operations before the Italian surrender.
        "Profanity is but a linguistic crutch for illiterate motherbleepers"

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        • #5
          Four submarines dont look like a big difference anyway. Only one would be on a active combat patrol on any given day.

          Dont usually cite other discussion threads for information, but this has some numbers and sources.

          http://forum.axishistory.com/viewtopic.php?t=105324

          I've no time to pick over the numbers or check sources, but this remark caught my eye. Perhaps I can check it later.

          From the linked discussion.
          "by Jon G. on 10 Dec 2006, 11:51 Further to the numbers posted by Andy, above, the 32 Italian submarines operating in the Atlantic sank an average of about 17,750 tons of shipping each, a slightly better average than the German boats operating in the Atlantic.The top scoring Italian boat in the Atlantic was the Da Vinci, which sank 116,686 GRT worth of merchant ships. In addition, Italian submarines sank 74,000 tons of merchant shipping in the Indian Ocean.

          Numbers from Sadkovich."

          The average may be 'valid' over the long haul, but I'd want to take German averages from circumstances similar to when & where the Italian submarines were operating in the Atlantic. The German numbers from 1939 or 1943-45 tend to drag down the average
          Last edited by Carl Schwamberg; 13 Jan 13, 10:42.

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          • #6
            Originally posted by Carl Schwamberg View Post
            Four submarines dont look like a big difference anyway. Only one would be on a active combat patrol on any given day.

            Dont usually cite other discussion threads for information, but this has some numbers and sources.

            http://forum.axishistory.com/viewtopic.php?t=105324

            I've no time to pick over the numbers or check sources, but this remark caught my eye. Perhaps I can check it later.

            From the linked discussion.
            "by Jon G. on 10 Dec 2006, 11:51 Further to the numbers posted by Andy, above, the 32 Italian submarines operating in the Atlantic sank an average of about 17,750 tons of shipping each, a slightly better average than the German boats operating in the Atlantic.The top scoring Italian boat in the Atlantic was the Da Vinci, which sank 116,686 GRT worth of merchant ships. In addition, Italian submarines sank 74,000 tons of merchant shipping in the Indian Ocean.

            Numbers from Sadkovich."

            The average may be 'valid' over the long haul, but I'd want to take German averages from circumstances similar to when & where the Italian submarines were operating in the Atlantic. The German numbers from 1939 or 1943-45 tend to drag down the average
            Were those Allied ship losses in GRT actually verified? The Italians also had a problem with inflating the size and type of their ship kills. One boat skipper claimed to have sunk the US Battleship California with a spread of torpedoes.
            "Profanity is but a linguistic crutch for illiterate motherbleepers"

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            • #7
              Although the Italian subs did not live up to the paper specs, there were also other technical and doctrinal issues. Italian subs were designed as fleet scouts and lone hunters which effected doctrine and design.

              Italian subs made a significant amount of diesel smoke on the surface and dived slower than German boats. Neither were problems to the Italians who expected their subs to patrol submerged most of the time, surfacing only at night to recharge their batteries.

              But if the boats were required to search on the surface as per German practice, crash diving only when threatened, both these issues became great weaknesses. They were especially problems when working within the range of land based ASW patrols.

              Italian subs were also expected to make all their torpedo attacks submerged, surfacing if necessary to finish off targets with their deck gun. Thus a very large periscope was fitted which increased the size of the conning tower in relation to other types of boats. This made their submarines easier to spot on the surface (especially by radar) than their German counterparts.

              These issues, as well as an inadequate communications fit (by German standards) made it difficult to blend Italian boats into wolf packs, and indeed they were employed as "lone hunters".
              Amateurs study tactics, Professionals study logistics.

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              • #8
                I was wrong about 1939 being a low year in tonnage per submarine. Ellis estimates it at approaching 50,000 tons per, with a avergae of 14 submarines at sea during the last quarter of 1939.

                In 1940 that rockets up to between 70 & 75 thousand tons per in the third quarter of 1940, with a average of 13-14 subs at sea each quarter. However the average drops off to under 10,000 tons per in the third qtr 1941, with the average at sea number rising to 33. A quick check against Huges & Costello 'The Battle of the Atlantic' confirms this trend & general numbers. It also confirms the complete institution of the convoy system from mid 1940.

                In the first quarter of 1942 the overall average per boat sunk rises a estimated 25,000 tons, with the average number at sea rising through 47, 56, 85, 99 subs at sea for each 1942 quarter. For the submarines involved in Operation Drumbeat during the first quarter the number hyperventilates to nearly 90,000 tons per sub (Ellis estimate).

                From the last quarter of 1942 there is a clear decline in tons per sub sunk. Dropping to under 5,000 tons avg. each.

                The original question concerned Operation Drumbeat - adding four Italian subs to it. If they average half that of the German per sub score in that campaign then 45k x 4 = 180,000 extra tons of US cargo sunk. It is possible they would do better against the unescourted cargo ships, and the USN handicap at that point was not in sinking the subs, but in getting a positive location.

                Overall the Germans sunk some 2,000,000 tons of cargo (not ship tonnage) destined for the UK in 1942. Adding a few percentage points to that does not change much. Conversely this period was the nadir in Allied cargo ship losses and a few percentage points addition ships sunk badly complicates the Allied cargo delivery problem in 1942. Concentrated on US shipping in early 1942 & the effect is even larger for the moment.

                I supose it is possible the Italian subs could perform so abysmally the difference would not show, but we need to better identify their actual sucess in terms of hard numbers.

                Comment


                • #9
                  Originally posted by Roadkiller View Post
                  ...

                  These issues, as well as an inadequate communications fit (by German standards) made it difficult to blend Italian boats into wolf packs, and indeed they were employed as "lone hunters".
                  Most of that reflects against the low sucess of the USN/USAAF locating German submarines during Op Drumbeat.

                  In the last observation I dont recall the Germans using pack tactics in Op Drumbeat. The number of actual subs on station off the US coast was very low. IIRC they were distributed across the entire east coast traffic lanes so as to spread the US ASW effort out. I could be wrong there, but dont have time to dig any deeper for information.

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                  • #10
                    You are correct, there were only 5 boats in Op Drumbeat and they did not work as a group. Not that they needed to in the environment they were in.

                    I just got carried away and forgot the original question
                    Amateurs study tactics, Professionals study logistics.

                    Comment


                    • #11
                      Hmm... the plot thickens. Five Type IX subs were in the first wave in January. The type IX were the only boats imeadiately available for realistic operations in those waters. I wonder what the technical differences between those & the Italian long range cruiser subs were?

                      The second & third groups dispatched were also primarily Type IX, with some Type VII. Since Germany had only built some twenty Type IX the gross fleet that could be deployed was severely limited. I also notice the claim on one German sub was confirmed as sunk by the USN from 1 January through 31 April.

                      In that context adding in one or two Italian subs on station makes some sense, even if inferior to the Germans. Even if inflicting far fewer losses they can add conservatively another 10% sunk at a time the Allies were in a bad way with cargo ship operations. A more optimistic 20% adds to the burden.

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                      • #12
                        Germany and Italy declared war on the USA on the 11th of December, '41.
                        The first 'Drumbeat' boat, U-125 sailed on the 18th, which is a pretty quick response. The last two sailed on the 27th, with all boats planned to be on station by the 13th of January.

                        Where were the big Italian subs? Could they have been made ready in two weeks?

                        It would appear that several Italian boats (LUIGI TORELLI, ENRICO TAZZOLI, GIUSEPPE FINZI, PIETRO CALVI) were used in the rescue of crewmen from the German supply ship ATLANTIS. It had been sunk in late November in the South Atlantic, so it would seem a large number of Italian boats were operting in that area at the time 'Drumbeat' was stood up.

                        Further, some Italian submarines such as the LUIGI TORELLI were operating in the Caribbean by Febuary '42 http://www.regiamarina.net/detail_te...&lid=1&cid=44/ )

                        The ENRICO TAZZOLI was off florida by March: http://www.regiamarina.net/detail_te...4&lid=1&cid=42 )

                        It would seem that those Italian boats that were fully operational were sent as quickly as they could, but perhaps there were no assets on hand to take part in Drumbeat?
                        Amateurs study tactics, Professionals study logistics.

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                        • #13
                          It would also appear that you will need to find 5 Italian boats to expect the same return as a single German boat, and this number comes from the Italians themselves!
                          " ... It is obvious that a single cause of inferiority could by itself be very serious, while the concurrency of all of the factors [cited], and [those also] omitted for the sake of brevity, becomes extremely serious.

                          Thus defining as 1 the war performance of a German submarine, and estimating only slightly lower the one of an Italian submarine for instance 0.8 the performance of an Italian submarine due to the combination of the seven more complex causes of inferiority which have been [previously] listed (if all of the causes are globally considered) reduces the performance to .8 to the 7 factor, or .21..."

                          And that's just to get hits, not necessarily sinkings:

                          "... This calculation, which serves as guidance, refers more than anything else to the chance one of our submarines has to perform its duties to the end: bring the torpedo to explode upon contact with the enemy hull. But if the weapon is instead, due to built-in defects, incapable of sinking or even seriously damaging the target, then due to this main deficiency, there is no longer any ratio which is worth computing. This one [deficiency] alone is enough to destroy the fruits of all labor, all fervor, and sacrifices of the entire submarine fleet..."

                          http://www.regiamarina.net/detail_te...53&lid=1&cid=4
                          Amateurs study tactics, Professionals study logistics.

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                          • #14
                            Originally posted by Roadkiller View Post
                            Germany and Italy declared war on the USA on the 11th of December, '41.
                            The first 'Drumbeat' boat, U-125 sailed on the 18th, which is a pretty quick response. The last two sailed on the 27th, with all boats planned to be on station by the 13th of January.

                            Where were the big Italian subs? Could they have been made ready in two weeks?

                            It would appear that several Italian boats (LUIGI TORELLI, ENRICO TAZZOLI, GIUSEPPE FINZI, PIETRO CALVI) were used in the rescue of crewmen from the German supply ship ATLANTIS. It had been sunk in late November in the South Atlantic, so it would seem a large number of Italian boats were operting in that area at the time 'Drumbeat' was stood up.

                            Further, some Italian submarines such as the LUIGI TORELLI were operating in the Caribbean by Febuary '42 http://www.regiamarina.net/detail_te...&lid=1&cid=44/ )

                            The ENRICO TAZZOLI was off florida by March: http://www.regiamarina.net/detail_te...4&lid=1&cid=42 )

                            It would seem that those Italian boats that were fully operational were sent as quickly as they could, but perhaps there were no assets on hand to take part in Drumbeat?
                            The German patrols along the US east coast ran on to April. It appears three relays were sent for somewhere between 18 & 24 sorties. That the high point in the losses did not peak until March supports this. If the Italian subs cant make it there in January then February will do.

                            Originally the question was soly about the four largest Italian subs. I'm getting the idea perhaps a dozen others could have been used as well. If so that might have made a bit of difference.

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                            • #15
                              Well, with 36 torpedoes they would have to have hit something...

                              If they could have been there before April, yeah, they would have done some damage.
                              However, they would have had to stay clear of the German subs. Put one on either side of Florida and they couldn't have helped but do well.

                              Would they have made it back?
                              Well, that's a whole 'nother question, ain't it?
                              "Why is the Rum gone?"

                              -Captain Jack

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