Tuesday, 31 March 2020

Slow Convoy (SC 7) October 1940 - Tonnage War Solitaire

In my post looking at using Vassal to allow boardgames to be played remotely, specifically War of 1812 that I'm playing with Steve M at the moment and part of a theme very much in vogue at present with social distancing important, I thought I might illustrate a solo module available that can also fit the bill in between painting and reading.

Tonnage War Solitaire is a Vassal module for a free to download paper game developed by Leonard Heinz, a game I remember printing out many years ago and playing on a holiday to France on a bit of down time in between days out at the beach or trips to the Normandy countryside.

Now you don't have to print the game and cut out the paper counters as everything you need to play is available on the Vassal site to download with beautiful digital counters representing the various ships and aircraft needed to play convoy battles in the North Atlantic.



Evidence of this excellent artwork is illustrated in the guide to reading the unit markers that is part of the module with many of the markers needed to record the status of individual aircraft and ships handled by the counters themselves with codes appearing on them when evading or attacking to help keep you informed of your progress through each phase of play.

The game is very much about numbers that generate the results - The various 'Attack Values' are the number needed or less on a D20 to cause a hit whilst the various visibility or asdic numbers likewise work to establish whether a contact has been made. With attack factors of 2 or 3 using depth charges, multiple escorts are the best way of going after U-boats often just trying to force them to evade and thus stop them attacking.

Those play phases recreate the often several days of attacks on a series of historic convoys included with the game, as U-boats controlled by the game mechanics of a U-Boat Reaction Table attempt to close with the convoy and with you the player looking to manoeuvre your escort assets of warships and aircraft to try and prevent attacks whilst also destroying the Nazi submarines.

Each phase of play consists of three U-boat moves and three Escort player moves representing four hours of battle with U-boats attempting to penetrate into the attack zones around the convoy and deliver torpedo attacks.

The zones surrounding the convoy formation are a neat division of the surrounding ocean that the escorts seek to monitor with radar and asdic (sonar to my US cousins, but seeing as we Brits invented both I will use the RN terminology).

The game recreates the 'wolfpack' tactics of the Kriegsmarine as the first U-boat in contact acts as a contact boat broadcasting a running commentary on the position of said convoy to allow other boats to move into the area to attack.

As the escort commander you are focused on trying to defend against those tactics by placing decoy escorts firing star shells to draw U-boats away from the merchantmen, identifying the contact boat and driving him off or better still destroying him, changing the course of your convoy to try and shake off the pursuit and of course attempting to identify and attack enemy submarines before they can attack the merchantmen.

In addition you may have or you can detail an escort to act as a rescue boat, picking up survivors from sunken shipping and thus reducing the victory tally of the enemy achieved from their sinkings.

So lots of decision points for the player in this game as you manage the assets you have whilst imagining what is was like for the real escort and convoy commanders managing their stress as well as their response to a merciless enemy.

The Attack on Convoy SC7 - The sinking of SS Assyrian - John Alan Hamilton (Imperial War Museum)

Slow Convoys, code-named SC, with a number to indicate their position in the running order, were convoys of older merchant ships, usually only able to cruise at about 8 knots, running east bound from Sydney Harbour, Nova Scotia, Canada often to Liverpool which started with SC 1 on the 15th August 1940.

Sydney Harbour and the Royal Canadian Naval base HMCS Protector from where the Slow Convoys started their passage to the UK.

A total of 177 slow convoys ran between then and May 1945, totalling 6,806 ships and with only three failing to complete the passage, but because of their slow speed, they were particularly vulnerable to attack, especially in the early war years when Allied escorts, their equipment and tactics were not as effective as they would later become.

Slow Convoy SC-7 was a 35 ship convoy carrying mainly lumber and iron ingots for the British war industry, but also included the 9,512 ton tanker MV Languedoc carrying oil for the Royal Navy and the British SS Empire Brigade carrying vitally needed trucks for the military.

Leaving Sydney on the 5th October 1940 and meeting up with a five ship escort of corvettes and sloops, SC-7 would earn the unenviable notoriety as the convoy that suffered the worst day's shipping loss, twenty ships, in the entire North Atlantic campaign.

The first two weeks of the voyage was principally concerned with coping with the storms and gales of an October North Atlantic, with several ships in the 35 ship convoy becoming separated and forced to make the cruise independently and with the Greek freighter Aenos being intercepted and sunk by U-38.

It was not until the main convoy entered the Western Approaches on the 16th October that SC-7 found itself under attack from a seven strong U-boat Wolf-pack that started to methodically pick off ships on the approach to the Irish Sea in a three day and night sustained attack.

It is at this point that the scenario contained in the Vassal package picks up and the snapshot of my game shows the position at 08.00 on the first day as the U-boat pack, following the location broadcast of the contact boat seen centre in the 'Inner Zone' (IZ), moves into the attack with four boats joining the contact boat and another moved in to the 'Outer Zone'.

The 'Good-Guys' from left to right - HMS Bluebell (K80, Flower-class Corvette), HMS Fowey (L15, Shoreham-class Sloop) and HMS Scarborough (L25, Hastings-class Sloop).

With just three escorts available, HMS Bluebell, Scarborough and Fowey, the other two due to arrive the next day as reinforcements, I felt compelled to remain in close attendance in the 'Attack Zone' (AZ) rather than to push an escort out in to the more expansive IZ in an attempt to hunt down the growing threat but leaving a quadrant undefended. This is when you start to appreciate the problems of the chaps that did this for real.

In addition to the growing threat from gathering U-boats I had six merchantmen in the straggler zone and out of formation thus vulnerable to attack whilst unescorted and with no rescue ship I could not afford to detach my limited escorts to rescue any survivors, unlike my historical predecessors who ended up loaded with survivors but thus spent more time in rescue work rather than fending off attacks.

The situation at 08.00 after the first four hours of the 17th October, with the wolf-pack gathering.

The convoy came under attack mid-morning on the 17th October as U-38, U-48 and U100 managed to move into the port, starboard and bow AZ's, evading the escort which failed all attempts to pick them up on asdic, thus seeing them sink six merchantmen.

At the midday point, day one, six merchant ships have been sunk and U48 and U100 can be seen regrouping away from the convoy after their attacks. They will have to see if they will be able to pick the convoy back up to repeat their attacks. The other attacking boat U38 has lost contact and is placed in U-boat Exiting box seen at the top of the display, one less to worry about! However another two boats are in the 'U-boats Entering' box meaning they are available to move in to make attacks.

The attacks continued into the afternoon as the remaining boats less the contact boat made their attacks, with the stragglers coming under attack but suffering no hits fortunately and with HMS Bluebell making a contact and forcing a boat to evade, but which managed to return and make an attack later in the day.

My escorts were being run ragged as the attacks continued on into the hours of darkness which allowed the U-boats still in contact to adopt their favourite tactic of moving in close on the surface.

The only effect my close in escort was having was that the U-boats were delivering their attacks from the AZ, perhaps to avoid my escorts whilst taking the time to move closer into the 'Convoy Zone, CZ' amid the merchantmen where any attack would have been even more destructive.

Midnight at the end of day one and the fury of the wolf-pack has been vented on SC-7 with only three U-boats  in contact with the convoy, the rest having broken off as illustrated by the boats stacked at the top in the 'U-boats Exiting' box, but having sunk 14 merchantmen.

As the escort commander, I was starting to feel like an observer of events rather than a participant as the tally of sunken merchants grew to fourteen as the midnight hour of the 17th October drew near.

Surely I had to get a break! Then it happened, as the elite crew of the Type VIIB, U-46 under their 'experten' commander, Kapitanleutnant Englebert Endrass, only just awarded oak leaves to his Knights Cross and his U-boat War Badge with diamonds started to move in to make a second attack, this time in darkness on the surface from the starboard AZ.

Type VIIB veteran U46 met its nemesis in the form of HMS Bluebell when sunk by gunfire whilst making a surface attack at midnight on day 1

As U-46 moved into the starboard AZ, HMS Bluebell rolled to see if she could spot the U-boat at night on the surface needing 4 or less on a D20 and scoring a '1'!

The tension grew as I then proceeded to check the first time intercept rules at night by an escort, replicating the chance of the escort catching the U-boat by surprise.

On a second D20 roll a score of 1 would see Bluebell sink U-46 by ramming but suffering damage herself requiring her to withdraw from the battle or score a 2 seeing the U-boat sunk by accurate gunfire.

Needless to say that the highlight for me as the escort commander was seeing the two appear in the commentary screen as the simulated die roll sound effect heralded the result - scratch one elite U-boat.

Victory! of sorts, with 14 merchants at the bottom of the Atlantic, but the elite U-46 joining them (bottom left in the U-boat Sunk Box) after being taken out by gunfire at night on the surface by HMS Bluebell. U-101 has managed to get into the stern AZ and is about to sink another two merchants before the day is over.

By the end of the 17th October SC-7 has suffered a terrible mauling, only slightly compensated for the sinking of U-46, but just four ships away from suffering the same fate as the historical outcome.

Reinforcements due 08.00 on the 18th October in the form of (left to right) HMS Leith (U36, Grimsby-class Sloop) and HMS Heartsease (K15, Flower-class Corvette) seen here after her transfer to the USN in March 1942 as PG70, USS Courage

As the early hours of the 18th October played out, the consolation of two more escorts, HMS Heartease and Leith due to arrive at 08.00 together with the fact that the enemy wolf-pack was now reduced to just two boats left in contact with it gave some hope to cling to as the scenario entered the second day.

It's 08.00 on the 18th October and U-101 is still regrouping to the 'Outer Zone, OZ' after its stern attack on the convoy, sinking two more merchants, and with U-123 acting as contact boat, but with the escort group now reinforced by HMS Leith and Heartseas upping my abilities slightly to intercept attacks should they enter the bow and starboard zones where I have placed two rather than a lone escort.

U-101 moves into attack

It took most of the morning of the 18th before U-101 had managed to regroup and sadly, for me and the convoy, pick up the position for another attack. With her sister boat closing in, U-123 maintained the role she had carried out throughout as the contact boat as my escort team attempted to guess where the next attack might be pressed and to present the best chances of interfering with it.

With just two enemy boats in contact with my convoy, I was now willing to change tactics slightly in that with my reinforcements available I determined to press any attack from interceptions away from the convoy on U-boats leaving after an attack, but preferably during an evade.

I could now take the risk of leaving a zone vacant temporarily whilst pursuing an asdic contact at least into the IZ, and hopefully taking out another u-boat.

Contact, bearing 045! - HMS Bluebell picks up U-101 on her asdic and calls in HMS Heartsease to make a concerted attack, pursuing the contact into the IZ after she had sunk another three merchants.

As U-101 moved into the IZ at about midday on the 18th I awaited the result of her attempt to get into the AZ. In the game, this is a randomised process with a D200 result identifying with AZ quarter the U-boat enters to make its attack.

Needless to say I was pleasantly surprised to see U-101 move into the Starboard quarter of the AZ where I had positioned Bluebell and Heartsease ready for such an event and offering me two opportunities to make an asdic contact.

A hopefully chastened U-101 in the OZ, survives the full out attack by Bluebell and Heartsease, IZ right, in what proved to be her final attack on the convoy, leaving the contact boat U-123 to make the final attack in the dark hours of the 18th.

HMS Bluebell delivered the required asdic ping and called HMS Heartsease to her support as both escorts delivered their depth charge attacks as U-101 lined up and delivered another salvo of torpedoes taking out three more merchants.

However this time I was determined to pursue the evading boat into the IZ as it withdrew and HMS Heartsease managed to keep the asdic contact allowing both escorts to deliver a second attack, which failed to claim a kill and saw Heartsease use up all its depth charges in the process - Well I did order an aggressive defence!

With all her sister boats departed, U123 moves in to deliver her attack on SC-7 after two days of shadowing the convoy. A nice touch in the game is that the board darkens to remind you that the visibility has shortened as darkness closes in.

As U-123 prepared to move into the AZ I could only hope it would be in the bow or starboard zone where two escorts gave me a better chance to intercept a U-boat on the surface as the light started to fade.

Fortune favoured the brave as U123 attacked through the bow AZ submerging to deliver a salvo of fish and taking out two more merchants just as HMS Leith obtained an asdic contact,to call in Fowey to support the counterattack.

U123 makes good its escape after taking damage in a depth charge attack from HMS Leith and Fowey

The first salvoes of depth charges missed and U-123 went deep to evade the pursuit as HMS Leith maintained asdic contact into the IZ.

I couldn't rely on U-123 losing contact with the convoy even though she wouldn't have a contact boat to give the position for a second attack and so I continued with my orders for the day and sent both Leith and Fowey off into the IZ in pursuit.

Success, Fowey and Leith continue to pursue U-123 into the IZ with HMS Fowey managing to damage the U-boat with its final depth-charge attack forcing it to break contact with the convoy. Note the U-boat counter marked with a red 'DA' indicating she was damaged in the attack.

Night attack by surfaced U-boats featured large in the game, culminating in the final attack by U-123

HMS Leith maintained asdic contact into the IZ and in the two attacks with depth charges, HMS Fowey managed to damage U-123 thus at least ensuring she would break off and the survivors of SC-7 could make their way to Liverpool.

Midnight on the 18th October and with four turns of day three,the 19th, not required SC-7 makes its way to Liverpool after its terrible battle with the wolf-pack. I ended up losing two more merchants than historically but managed to sink and damage two U-boats in return, producing a remarkable simulation of the actual events

This was a great game and I really enjoyed the tension generated as the U-boats move into the attack coupled with the exhilaration of pressing back with a counter-attack by the escorts.

This early period of the Atlantic Campaign seemed to be well modelled with a weak escort force forced very much on to the defence with little opportunity of breaking up and disrupting a building U-boat attack.

I could have tried a change of course on day one to shake off some of the threat but may well have ended up with more merchantmen in the straggler box as a consequence. The thought of using a decoy escort or detaching one as a rescue ship was dismissed early due to my limited numbers.

With more escorts and of course air support there is a greater opportunity to take the battle to the U-boats as they advance across the OZ and IZ to make their attacks and the later scenarios should offer that potential, although facing more U-boats as well.

The next prepared scenario is another slow convoy out of Sydney, SC-48 which takes place a year later on the 14th October 1941 over five days and with a lot more escorts and aircraft involved, including a US escort group that historically saw USS Kearny damaged by U-568 that raised tensions further between the US and Nazi Germany.

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