(A. MASSED U-BOAT THEORY)
This is the first of several planned appendices outside the weekly format dealing with issues tangential to the overall campaign (and making up for the sparse posting that the weekly format entails).
Baltasar raised the important question of how exactly the submarines will be deployed, and in particular whether they will be deployed en masse.
Historically, the submarine force was never deployed in the numbers or concentrations that I intend. In 1939, only 26 U-boats made patrols between the beginning of operations in August and the end of the year. In September 1937, I have over 100 U-boats ready for immediate duty.
Historical U-boat deployments were extremely spread out, with missions to defend Scandinavia from invasion, interdict shipments to Allied forces in North Africa, attack American shipping off the North American coast, patrol west of the British Isles to report inbound weather off the Atlantic for the benefit of the Luftwaffe (!), and even support Japanese operations in the Pacific. I don't rule out the potential for most of these as side operations, but the main focus will always be WO I and the defeat of Britain.
In HoI3 terms, even a single flotilla would be unusually numerous as a concentrated anticonvoy force. U-boats tended to attack alone, and even when coordinating attacks, they would be unlikely to engage simultaneously. This is partly due to the difficulty of intercepting a convoy or task force with a U-boat while remaining undetected (as U-boat top speeds tended to be lower than warship top speeds, especially for submerged U-boats), also partly the difficulty of finding targets at sea (German radar was inferior at best, and scouting by air was largely unsatisfactory), and very critically a justified paranoia about radio transmissions that limited communication with deployed U-boats. (The Allies could often decipher messages to and from U-boats, and whether they could read the signals or not, they used direction-finding equipment to triangulate the positions of submarines making radio broadcasts.)
With these things in mind, there are two branches of U-boat attack theory that I want to pursue. The first is convoy warfare, and it will probably be fairly recognizable to students of the war, particularly in its initial stages. Since a convoy isn't represented in game as an actual unit in the sea, but rather as a route, the way to engage convoys is not through ordering direct movement and attack, but rather by setting up pickets where convoys will travel.
HOME PORT PICKETS are the most basic deployment. In this system, U-boats lurk in waters near British ports and sink traffic as it arrives and departs. There are three major advantages to this system: 1. it requires the coverage of only a small area (permitting concentration and limiting the minimum number of boats needed to be effective), 2. it involves very short operational ranges (even from Wilhelmshaven, the obsolete boats in Claasen's command can participate), and 3. nothing bound for Britain can avoid the blockade entirely. There is also, however, one overwhelming disadvantage: home port pickets will be well within range of British radar warning systems, air patrols, and whatever fleet assets they have in home waters.
MID-OCEAN PICKETS are a little wilier. This method involves a line of U-boats strung through the Atlantic, seeking to detect and converge on convoys. It's something of the opposite of home port pickets. The advantages is that the dangers of British defenses are limited by the vastness and remoteness of the mid-Atlantic (as well as the greater dispersal of boats). The disadvantages are that 1. the U-boats are dispersed, limiting the damage they can do when attempting to converge on located convoys (historically, the boats would often scramble and not make it in time to catch the convoy, and it was also a bad occasion for dangerous radio traffic), 2. the U-boats are unlikely to cover the entire area, allowing some convoys to slip through, and 3. moderate range capability is required, ruling out (in my case) Claasen's boats (although France could change that). The nature of the mid-ocean picket changes depending on how near the coast the boats dare to set up. Boats on weather-reporting duty (both U-boats and trawlers) functioned as a mid-ocean picket in the real war, but the frequent radio communication required for weather reporting interfered with their effectiveness in that role (and made them targets for British operations to capture German encryption materials and devices, worsening the problem).
FOREIGN PORT PICKETS are a more daring option which potentially combines several drawbacks. A foreign port picket pulls the home port picket routine, but overseas. This would absolutely require extreme-range boats and could potentially be just as dangerous as patrolling the Thames, depending on the local ASW capability. The United States is the logical target if necessary, but if they don't have Japan drawing off part of their navy and air force to the Pacific, I'd be skeptical of the overall utility of the gambit. (For this reason, if America declares war on me I will try to bring Japan into the Axis.) Also, the foreign port picket will only intercept traffic from that port, and not all the traffic involving the British Isles. A mass foreign port operation is probably only worthwhile in the case of the USA entering the war. Minor foreign port pickets might be useful in lightly-defended areas such as South Africa or South America, but advantageous bases (via Spain, perhaps?) would be crucial, and that's in addition to extreme range capabilities that I simply don't have currently and am not sure I can afford to prioritize.
KNOWN POINT PICKETS would be large clumps of boats staking out established convoy routes in the middle of the ocean. Without clear intelligence on the convoys, this would be an all-or-nothing maneuver, as a bad location would tie up an entire operational group and produce no results. There's also the danger of a massive, organized ASW response. This concept is an experimental one.
From Silent Hunter III, map detail of convoys and air cover in the vicinity of Britain. Note grid reference system; this means of designating locations was intended by the Germans as a layer of encryption (as opposed to the internationally recognized latitude/longitude system).
The second branch is, of course, attacks on task forces. These specifically tactical ideas are impossible to implement directly in HoI3, but I intend for them to demonstrate that mass U-boat operations against large groups of warships are not unthinkable.
FLAYING is a standard operational procedure for lone U-boats encountering task forces. In the absence of a good shot at a capital ship (likely because of screening), lone boats should attack screening ships (primarily destroyers) and then escape. The more screens are sunk, the better the subsequent chance of a U-boat or mass of U-boats eliminating the central elements of the task force.
HORSESHOE is a task force attack pattern involving a significant contingent of U-minelayers (at least six). These minelayers are directed to the path of a task force, where on short notice they lay prearranged minefield segments that form a horseshoe shape intercepting the enemy warships. The "bottom" of the horseshoe, directly in front of the taskforce, should be deep enough to convince survivors to divert course, whereupon they will strike the mines on the sides. Encountering mines seemingly in all directions, the remains of the task force may even consider themselves stranded. (The rear can be mined lightly as naval groups don't like to backtrack from their intended destination, particularly once indoctrinated withzigzagging ASW techniques.) The minelayers might also reserve the option to loiter around the field and add some torpedoes to the festivities (Allied crews might even mistake wakeless G7e torpedo attacks for further mines). U-minelayers were real historical boats, but they mostly mined ports, where mines are expected (and quickly charted and swept) and sinkings are shallow. (Many ships sunk in port were simply raised and returned to service.) A hasty minefield on demand in deep water would be extremely dangerous. German mines had twice the explosive of German torpedoes, and exploded beneath ships to directly damage keels (like the most damaging torpedo shots). This kind of attrition could seriously cripple the Royal Navy. A major drawback to this tactic, though, is that it leaves an unreported minefield in the ocean where German forces may blunder into it. (It wouldn't be radio-safe for the U-minelayers to indicate the field.) This is, however, something for naval command to plan around, hitting task forces when they're off normal U-boat sealanes. Once the minelayers reach port, information on the minefield can be distributed.
The roles of different minelaying boats in a five-boat horseshoe. Depending on the reliability of information about the target and the steadiness of the target's course, the horseshoe could be "shallowed out" for greater uncertainty, with the flotilla arranging a wider pattern by rendezvous and the middle three turning their patterns sideways.
THORN DANCE is a task force attack pattern involving around 30 standard, torped-capable U-boats. A single, deeply coded and seemingly innocuous signal from headquarters indicates a time and place at which a task force will be attacked. Each boat lines up on a prearranged, boat-specific heading from the central location, roughly 1500 yards from where the fringe of the task force (hopefully attritted through flaying, allowing close proximity to the capital ships) is expected to be at that time. Via surface maneuvering and hydrophones, boats can position themselves relative to each other. Each U-boat lurks at a deep depth (certainly deep enough for the task force to pass over) until the task force (detected via hydrophones) has progressed to the center of the formation. At this point, the subs rise to periscope depth, line up their best shots with a slight (though not wholly decisive) preference for ASW-capable ships, and fire narrow salvos (perhaps with about 2 degrees between torpedoes) from all fore tubes. The torpedoes are set for shallow run depths (e.g., 1 meter) and contact explosion, meaning that they are unlikely to strike U-boats on the opposite side of the task force. The U-boats then descend to predetermined depths, interleaved among adjacent boats to minimize the risk of an underwater collision (or depth-set depth charges), and reverse course, initially by backing and then by turning around. In the event of active pursuit from convoy survivors, U-boats should carefully target shots from their rear tubes (rising to periscope depth if necessary), or possibly fire homing torpedoes (although this would require all U-boats involved to run quiet for safety reasons while escaping). (As of September 1937, I already have the Zaukönig I homing torpedo researched.)
I have a feeling practical considerations might make a mess of this, but it's worth trying.
FIRING SQUAD is a simplified Thorn Dance intended for smaller groups, and something that can potentially be put together on the fly, possibly by a surface rendezvous in which captains shout back and forth by megaphone (the British are less likely to be able to eavesdrop on this unless they have built a giant hearing trumpet in Cornwall) or flash terse one-time pad morse code at each other with topside lights (these are both good general interboat communication methods for any of these operations if such communication becomes truly necessary). A handful of subs take up positions around a spot the task force is expected to cross, attack together following the lead boat's attack, then support each other's escapes. This is compatible with some degree of minelaying, and the initial signal might be the task force striking the mines, rather than a torpedo shot. Bluntly, Firing Squad is a somewhat recognizable take on the coordinated wolfpack.
A disinformation campaign about secret weapons will be conducted, focusing on creating the impression that new torpedo types and capabilities exist, including externally-stored torpedoes which seem to be capable of direct launch, torpedoes which deploy decoys at a set distance (which may or may not be worth developing for real), markings on torpedoes and new design features which appear to allow a new modular component (that does not exist) to be inserted into the torpedo, and a number of torpedoes marked with a purple nose stripe that crews are simply told is "top secret" (to hopefully confuse the Zaukönig issue, as it would be trivial to develop countermeasures (i.e., over-the-side noisemakers, or even depth charge patterns to confuse the torpedo) for acoustic tracking if it were understood; this is what happened historically). Early deployments of Thorn Dance and Horseshoe are ideally going to result in chaos and confusion on the Allied side, and that can be exploited to stifle the development of countermeasures. I'd rather they were afraid of an imaginary supertorpedo than methodically planning ways to handle what's really going on.
All of this hinges on secrecy and undetectability. Mass attacks should probably not be conducted near the British coast, in order to avoid air patrols and land radar. Encryption research would do a world of good (and decryption research would help too, for targetfinding). Serious precautions should be taken to keep the content of radio messages concerning these operations impenetrable, and to relieve U-boats at sea of the need to send any preparatory signals at all.
EMPTY EYES is a new set of naval communication standards applying only to U-boats and primarily to massed attacks. In general, U-boat orders are issued when the fleet sails and not updated, and U-boats are strongly discouraged from broadcasting status reports (which are strictly forbidden if the fleet has been sent out to attack a task force or mass in a known mid-ocean convoy point). Aborts in particular are to be done silently, as if one boat is aborting from something, there will be other boats in the area. Only designated scout boats will radio contact reports, and they will attempt to do it a significant distance from other submarines. U-boats will not identify themselves by radio unless it is for some reason necessary. Another sensible thing to do would be to detail a couple of flotillas to run around the North Atlantic sending bogus signals in U-boat naval Enigma, with corresponding traffic from headquarters. Real boats will know these messages are false because they'll be in disused keys (the primary seed for Enigma encrypt-decrypt is a three-letter code).
Most of all, orders to fleets engaged in Horseshoe, Thorn Dance, or Firing Squad operations must be short, simple, and utterly opaque. To that end, as many of the associated details as possible are prearranged with the captains. Only the captains, the fleet commanders, and the relevant admirals know anything at all about these plans, which are only written down in a single secure place: tattoos on Assmann's back. (Assmann is forbidden to sunbathe before the end of the war.) With so much vital information entrusted only to captains, boats on special assignment are instructed to return to base if the captain is killed or incapacitated rather than risk them fouling up an organized action with independent operation (such as blundering into a Horseshoe).
INFORMATION PROVIDED TO DEPARTING U-BOATS
* explained to captains in port
... fleet composition
... general patrol zone
... local patrol zone (different for each boat)
... which boats are designated contact reporters
... contingency rendezvous signals and points, non-radio wherever possible
... for Horseshoe, the boat's designated minelaying pattern
... for Thorn Dance, the boat's designated heading and depth preference
... two points which designate a line used to further encrypt positional information
... secret radio protocols for identifying a camouflaged attack order
* distributed to radio officers
... this-operation-only contingency signals (on water-soluble paper)
... standard encryption/decryption (i.e., Enigma materials and devices)
* explained to crew
... nothing
The signal initiating an interception and attack has to be completely secure and not rouse any suspicions. Therefore, not only is no response given to it, but it is also disguised as a routine order to a lone boat in a different area. The nature of the order and the boat are explained to the relevant captains, but not to the decoy boat itself, which should faithfully carry out the dummy order as normal. The coordinates of the order given to the decoy can be reflected over the secret plotting line given to the captains participating in the attack in order to reveal the location of the ambush.
An example of a double-meaning order giving an encrypted intercept point. Further refinements could include time information in the hidden message as well as indicate the target's own heading. Minelayers are particularly good fodder for this ruse because it is common sense that laying a minefield would be the subject of relatively dense radio traffic involving precise locations, and an enemy force doesn't need to be in the area at the same time to make it plausible.
Cybvep, essentially the entire army is under the command of von Epp, whose headquarters has both AI Control and AI Reorganization enabled. I will probably leave it that way for the most part. I reserve the right to break off formations for operations outside of the primary WO II framework, particularly should I have the need or opportunity to reinforce the Italians in North Africa. Nearer to the present, I may directly (or via a finer grain of AI control) control a contingent assisting Nationalist Spain, and more speculatively, I may do Sealion myself. If worst comes to worst and we find ourselves at war with the USSR, I plan to split that off into a separate AI-controlled command so that von Epp doesn't have to worry about it and I can more precisely allocate forces to that front.