The Home SC Theory

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The Home SC Theory

#1 Post by Amwidkle » Sat Jan 22, 2022 7:37 am

As I’ve deepened in Diplomacy experience and developed my play style, I’ve come to appreciate that, although each supply center on the board grants one unit, not all supply centers are of *equal value.* The positioning of supply centers on the board in relation to your country also matters, and should be factored into tactical and strategic considerations.

One handy heuristic — “Home” supply centers (meaning the supply centers you start the game with) are inherently more valuable. I would even go so far as to say that a home SC is nearly *double* in value as a non-home SC. But why?

Most obviously, home SCs are the *only* centers where you can build new units. No matter how large your empire expands, you’ll only ever have 3, or in Russia’s case 4, home SCs. If your home centers are lost to an enemy, or garrisoned with your own units because you’re mounting a defense, then any successes elsewhere on the battlefield automatically become less valuable because you may be prevented from actually utilizing builds from any future SC gains.

Let’s consider the example of Austria, which is universally considered the #1 most vulnerable nation to an early downfall. Why is this?

In S01, virtually alone among nations, Austria is in danger of *instantly* losing a home SC to a neighbor, through Italy’s Ven-Tri attack. (Technically, Italy can lose Ven to Austria in S01, but due to the construction of the map, that’s exceedingly rare — and even rarer that Austria could successfully hold Ven in F01.)

Austria’s problems don’t end there. Italy has an alternative S01 attack path through Ven-Tyr, Rom-Ven. Italian armies in Tyr and Ven menace Austria’s home SC of Vie, *or* could execute a supported attack on Tri.

It’s still not over! In the East, an S01 Russian invasion of Galicia places two Austrian home SCs (Vie and Bud) in jeopardy. A Russian A (Gal) is enormously awkward to defend against even without a hostile Italy, and near-fatal if Italy is also hostile.

This brings about some interesting corollaries. I question the orthodoxy (promoted in Richard Sharp’s “Game of Diplomacy”) that Austria and Turkey are virtually destined by geography to be antagonistic. In fact, of all his Eastern neighbors, Austria actually has least of all to fear from Turkey in 1901. While Greece and Serbia (sometimes Rumania) may be contested between A/T, for Turkey to even come close to menacing a *home* Austrian SC takes significant time.

Almost everyone would agree that a Russian army in Gal (bordering Vie/Bud), or an Italian army in Tyr (bordering Vie/Tri), are infinitely more threatening to Austria than a Turkish army in Bulgaria, which borders Ser/Gre — considered Austria’s neutral gains. Why would that be the case, unless home SCs had an inherently greater value than neutrals?

Consider also the common scenario of Italy defending against a Turkish fleet in ION. Often, Italy will have a fleet in TYS and have to choose between defending Tun or defending Nap. The home SC theory suggests Nap in almost every case is the more valuable SC to Italy. The loss of Tun can be endured; the loss of Nap is a crushing blow, and a foreign unit in Nap also happens to directly menace another home SC: Rom. If you’re Turkey, you can use this knowledge to try to out-bluff your opponent, baiting Italy into covering Nap while you sail into Tun. Or if you’re Italy, and you expect him to do this, you can double-bluff Turkey by covering Tun instead! (Don’t try this at home, kids!)

Another strategic corollary of the Home SC theory is that, when assessing your diplomatic options, you must generally regard any nations attacking your home SCs as *mortal enemies.* Skirmishes taking place farther afield (say, in the Balkans, or in Scandinavia or the Low Countries) simply must be assigned lesser importance if you’re being attacked at home. It’s possible for France to get along with Germany even if the latter occupies Belgium — not so if German troops are in Paris.

This article has been mostly focused on tactics. But diplomatically, your rivals are much less likely to ally with you if they see your homeland being torn apart. It’s not just a tactical but also a psychological disadvantage. It brands you as a “loser.” Don’t let it happen!

Most newer players are optimistic and excited by grow, grow, grow. I would instead describe my playstyle as pessimistic and defensive: projection of strength begins with security at home.

If you feel the same way, turn the Home SC Theory to your advantage!

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Re: The Home SC Theory

#2 Post by JECE » Thu Jan 27, 2022 6:40 pm

While it is undoubtably true that controlling your home SC's is critical to the survival and expansion of all the Great Powers, I think that there is some flexibility on whether one chooses to prioritize their defense.

One thing that I try to do is use my units in other theaters while at the same time keeping an eye on how I can 'teleport' units back to the home front if I face an emergency. Convoys are very useful for this purpose, as is purposefully getting my units dislodged so that I can rebuild them back home.

In my own experience playing Russia, there is even something to be said about defense in depth. It's tricky to get right because you absolutely do need to keep supply center losses at a minimum when you are facing an invasion, (and unlike the real-world Russia, there aren't many places that Russia can retreat to in Diplomacy) but it is possible!

One particular consideration to keep in mind is the difference between Spring and Fall phases. It can often be beneficial to lose a home SC in a Spring phase if you have a better shot of occupying it in the Fall phase. If done right, you can even force disband an enemy unit in the process, which gives you valuable time as that unit is removed from the frontline.

In general, I favor a ju-jitsu sort of tactical mentality. If I know where my opponent is likely to move, I can plan countermeasures accordingly. Just because the enemy has reached my homeland, that doesn't mean that I would abandon that tactical mindset.

That said, if I intend to launch an invasion of another Great Power, I absolutely would plan a decapitation strike against my opponent's home SC's, since I can then maneuver to force disband their remaining units without worrying about them getting rebuilt. Once the enemy's home SC's (or most of them, anyway) are firmly under my control, and their unit count drops to a manageable level, I then usually try to enter negotiations with my vanquished foe.

Why? Because their remaining units are already on the frontline, whereas my home SC's are far from the frontline, and it would take years to bring my new units from my home SC's to the frontline. In fact, if possible, I would be very happy leave a home SC under foreign occupation if it lets me control a foreign unit on the other side of the board.

I do like your point about Austria-Hungary and Turkey collaborating! It's especially amusing if you trust each other enough to stage fighting and disputes against each other:
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