WATU Wargame Report 2023

On Saturday 6^th May, the Western Approaches Tactical School was once again operational in Derby House for a celebration of the wargaming Wrens of WATU and the 80^th Anniversary of the Battle of the Atlantic. Analysts and wargamers from WATU’s direct-descendant organisations—Dstl, the Maritime Warfare Centre, and HMS Eaglet—took up the roles of WATU Wrens, RN Convoy Escort, and dastardly U-Boats, joined by folks from Defence Academy Shrivenham, US Navy, McGill and York University.

Our WATU Wrens and players were a mix of new wargamers and old hands, men and women, professional and hobby wargamers, serving and retired naval officers, and academics.

The challenge on the Tactical Table was the night of 6^th/7^th May, 1943. A moderate sea, bright moonlight, and intelligence reports of five U-Boats operating in the vicinity of (the entirely fictional) Convoy ONS 506, a slow convoy comprising 12 ships sailing for Halifax. Escort Group B7, consisting of HM Ships D1 (destroyer and Senior Officer Escort), L1 (Black Swan class sloop), and Flower class corvettes P1, P2, P3, and P4, were in Night Escort Six disposition. A substantial wolfpack attack developed at midnight, beginning the game with the torpedoing of the merchant ship in column 3 row 2.

Here’s what the first view-giving looked like, and the same plot from the Wren’s perspective:

The gap in the convoy is our sinking merchant ship. Where could the U-Boat be that fired the torpedo? How many other U-Boats are making an attack? Their tracks are plotted in red pen to hide them from the players. The U-Boat positions are highlighted on the right for clarity, the star is a mischievous shoal of fish.

The first view-giving included the burning wreck of our merchant ship and a surfaced U-Boat sighted at the rear of the convoy. L1 closed for an exchange of gunfire, here is their (and other’s) orders:

Our players had a copy of the relevant parts of the Atlantic Convoy Instructions, including Op: RASPBERRY, which was quickly ordered and developed two asdic contacts at the front of the convoy.

Our Wrens made use of the adjudication tables to decide which of the in-range radar (all of them at this range), asdic and visual contacts to report. Here’s a few turn’s worth of contacts for L1, and a large stack-o-signals:

Oh goodness, there were signals. There were so many signals. WATU had a team of three Wrens and an RN Yeoman handling signals: players handed in signals to be sent, the Wrens copied them to all recipients, and delivered them after some transmission delay. In our game, Lynn O’Donnell handled everything, and our players sent so many signals that we ran out of paper. Here’s a few of them:

While all this was going on, visitors to the museum were grilling Paul and Lt Phil Roberts RNR (Rtd) about the game and the history:

Meanwhile, some familiar faces, and actual submarine warfare officers, were busy plotting the demise of our convoy, upstairs in Admiral Sir Max Horton’s office. While submerged, they didn’t get a look at plot, when surfaced they could peek out the window down onto the plot in the Map Room. Their orders and contacts were sent over the museum’s wifi:

How did our Escort Group do?

It was carnage in the convoy! Six merchant ships lost. But the Escort managed two creditable depth charge attack runs, one of which forced the target to the surface in what was likely to be its death-throes. They also avoided depth charging the shoal of fish (which was mostly down to failing to get an asdic contact rather than good judgement…)

Here is the 1943/2023 edition of the After Action News, hot off the press:

WATU NewsDownload

See also Report of Proceedings from MacKay, RNWR, in command of sloop L1, here.

How realistic was the game?

Well, there are a few reasons why the U-Boats had the upper-hand:

Firstly, in the interests of a fun time for all, our U-Boats all started within 2,000 yards of the convoy. In reality, U-Boats tended not to attack simultaneously like this. Particularly not when using pattern-running torpedoes (as we were), because of the risk of friendly-fire incidents.

Second, we only played 12 minutes of game-time, and an engagement is typically 30 minutes plus. Knowing we were unlikely to play out 20 minutes, we started in-media-res with the U-Boats well inside radar contact range and the extended screen. It’s likely at least some of our U-Boats would have been caught further from the convoy, allowing time for interception before they were able to get off any torpedo shots, which would have improved the score sheet for the convoy somewhat.

Third: the score sheet seems to favour the U-Boats, but one U-Boat was probably not going to survive the next 2 minutes, and the other two were not going to cause too much more trouble for a time. If the game had gone on longer I think we would have seen the tide turning in favour of the Escort.

Finally, the losses seem pretty high, but our convoy was extremely small (for convenience, and for interest—a bigger convoy would mean spending most of the game steaming to get near-enough to contacts to do the fun stuff). The whole point of the convoy system was that the losses were similar regardless of the size of convoy; a bigger convoy would have lost proportionately fewer ships.

In terms of the gameplay: it was certainly a lesson in communication between the Escort players, to co-ordinate a response to contacts without the screen descending into magnet-ball. The outcome of actual attacks were pretty realistic: with a lethal range of only 7 yards, depth charge attacks were about 10% effective. U-Boat kills generally came from hunting to exhaustion, which Escort Groups could not afford to do—this is why Support Groups were introduced in March 1943. We didn’t have enough players and Wrens to support more than six in our Escort, so even if we’d played longer, the chances of killing the submerged U-Boats were small.

The ploting & adjudication rules revision/expansion/better-recreation since the 2018 game made for a much more interesting game: the U-Boat players were thinking about more than just shoot-dive-hide, and there was a passable attempt at RASPBERRY from an Escort group who (with the exception of the Senior Officer Escort) had zero experience of ASW tactics.

I want to thank the Western Approaches Museum for hosting our game and giving us free-run of the Map Room, and about thirty Dstl & MWC folks who took part in the playtest/training games as well as the Big Event. It was pretty special to play a Derby House Principles wargame in the actual Derby House. I had an absolute blast. So did Tom’s U-Boat (har dee har) !