What would happen if the German Empire discovers Equestria and the German Kaiser personally meets with Princess Celestia and Luna? What kind of things would they be discussing? And what would be the outcome of the discussion?

German Empire meets Equestria, I have a lot of ideas for this, but I'm going to assume a number of things for my purposes.

1. The link between the two worlds is a portal of sorts, (whether the initial contact is caused by going throught the portal first or the portal appears afterwards can be debated)

2. the portal is or will eventually be of reasonable size, for this to work i estimate that the portal needs to be 110 ft wide, again whether this portal is always open or it can be manipulated with can be debated)

3. The portal should be in the sea, putting on the land causes a number of diplomatic, economic and social issues in both short and long term.

4. Germany makes first contact or is the first to be contacted. (depends on who arrives and or leaves) so the portal should be close in proximity to the German Empire

I put the portal in the German Bight, southeast of Heligoland

5. I considered that if Germans are the first to cross the barrier, then It could be made interesting by the sudden disappearance, and sudden appearance of a small German flotte, around this area in 1906.

6. Why 1906? A few reasons being Kaiser Wilhelm II and the navel race between the German Kaiserliche Marine and the British Royal Navy

7. As for the ship that disappeared I figured it to be something like this

Missing!
One German Fleet

Lost in German Bight, August 1906
Contains:
1 Deutschland class Battleship: SMS Deutschland (Lost in search of Following)
1 Königsberg class Light Cruiser: SMS Königsberg
1 Imperial German Yacht: SMY Hohenzollern II
1 German Crown Prince Wilhelm

And he would be our main (German) pov character for some part of the story

Crown Prince Wilhelm

How livid would Kaiser Wilhelm II when his son and heir apparent just disappears along with the Hohenzollern Yacht, the SMS Königsberg, and one of Germany's new Battleships, the SMS Deutschland.

There would be many an angry letter to George the Fifth, when the Kaiser thinks its the UK's doing

One of the issues that prince wilhelm will need to solve is preventing an Anglo german war from breaking out due to "I'm dead due to a british super weapon" circumstances

I've got lots more material for a story like this (at least for the German part of it).

If your interested I'll post some more ideas

As for the official Eqestria/Kaiserreich meeting between Kaiser Wilhelm II and Princesses Celestia and Luna. We can assume some things will occur.

Mutual Recognition of the nations of The German Empire and The Co-Principality of Equestria

An agreement of about the trading of knowledge between the worlds
(at this point I'd like to point out that the rest of Europe is going to expect an official World summit with equestrian representatives to take place in Geneva)

Perhaps some sort of exchange system between universities in Germany and Equestria.
(Twilight Sparkle, Proud Graduate of The Humboldt University of Berlin)

Procedures for the travel, residing, and immigrating of ponies to and from Germany and vice versa. (Visit Beautiful Germany Today for a change of scenery) (Equestria might become the new big tourist spot for Germans)

Trading agreements between the Kaisereich and Equestria.(Given the portals location, Germany will be equestria's #1 importer of goods, and Germany's economic sphere in china just became mostly redundant.)

Treaties allowing Germany to construct: an Embassy in Canterlot, an economic trading concession on equestria's coast (wherever the portal on equestria's side is, maybe baltimare? Somewhere else?) as well as allow Equestria to have its own legation in Berlin, and it's own trading on Heligoland.
(That island's importance to the German Empire is on the rise)

I assume that there might be a plan for Germany to supply Equestria with specialists and experts as well as allow Pony Experts to study German Tech for industrialization purposes.

If Equestria is going to keep other great powers from reducing it to european colonial possesions (a scramble for Equestria, has a nice ring to it), it will look to the german empire to modernize both its economy and it's military
(Equestria will most likely have quite a few orders to german arms factories)

A German-Equine non-aggression pact

And many other things that will shape these two worlds future.

It would probably be a good idea to make sure that Kaiser Wilhelm Doesn't do anything he's gonna regret on this trip, he doesn't have a good track record on being a diplomatic person. I assume that Crown Prince Wilhelm will be the most knowledgeable Person for the job since he's gonna spend the better part of a month or so in equestria,so it'll be up to him to set the diplomatic groundwork.

As for Where this takes place.
Crown Prince Wilhelm, by the time this is brought up, will has no objections to it being in equestria, and a state visit to equestria by all european leaders will eventually happen. Although, Wilhelm II might be skeptical on traveling to stranges lands.
So I think that Wilhelm III would have already sat down with the princesses anyway, and they would have this meeting in Germany. After which the kaiser might have a state visit.

That's my take on what will occur due to this meeting any other ideas and feedback would be appreciated.

For the economic and diplomatic effects this would have on Europe, that depends on how the great powers take the new world.

I assume every head of state will have to make an official press speech about Equestria and it's natives once it makes the front page. (If a portal to another planet doesn't make the front page of every paper, I don't know what would)

So it will be up to those groups of men to shape Human-Pony relation for decades depends on their take of it.

Would Europe see them as viable trade partners and potential citizens, as strange beings that aren't like us but are tolerable, or as animals that will be persecuted.

To the British, such an event might bring Britain's global dominance into question. The sun may never set on the British Empire, but Princess Celestia controls it. Britannia rules the waves, but now the Royal Navy only sails upon half of them. To the other colonial powers, Germany is dominating the Equestrian market, the Britain would, at least, want to make their presence known, to make sure that these ponies know the might of Great Britain. (I'd have expect them to march into Canterlot with Cavalry, to let that sink in)

France would see its old enemy exploiting the Equestrians, and it's up to the French Republic to protect them from the Germans. While French companies might make its way into Equestria, I see them gaining more prominence with other races and ponies in the other world. (French-Prench Cooperation?) Even then, France will probably not treat them as equals for a while.

Of course, to Germany, being more than tolerate to their new neighbors (Puns :P ) is expected, the crown prince respects them, chances are the kaiser does (eventually).

Not only will most of the Equestrian trade be with Germany (Equestria might get a Zollverein invitation), Equestria will also become more industrialized with German help and German goods.

I expect there will need to be a Bit-GoldMark exchange rate.

Since the portal is so nearby, I have no doubt that both Europeans and Equestrians will travel between the worlds and maybe even settle down. With the way certain regions are in Germany, Some ponies might travel/immigrate to certain areas in greater numbers

The Pony population will obviously be higher for the areas of Hannover, Hamburg, Bremen, and Schleswig-Holstein, those areas being the closest to portal, Berlin will also gain a Pony Minority (because it's the capitol)

Now for The different Pony types and their place in Germany

Unicorns: Their high intellect and pursuit of knowledge puts them into professions of Scientists, Professors, Business Owners, Merchants. They would have greater numbers in cities such as Hamburg, Cologne, Berlin, and München. Expect a number of unicorn students and professors (soon) in Germany's Universities such as Leipzig, Königsberg, and Marburg. Unicorns ability to utilize Magic* also would have them working for the German Government in R & D

*(Pony Magic and its effect on society will probably need its own article)

Earth Ponies: Their strength and skills with plants and animals make them renowned in Europe's agriculture sector. With larger populations in Pomerania, East Prussia, and West Prussia. While some earth ponies come to Germany to establish farms, many settle to work on the Large Prussian Junker Plantations or study Europe's advances in mechanized farming

Pegasi: Their flight and cloud manipulation capabilities have them appearing across the nation in many careers. The largest employer of Pegasi is the Kaiserliches Postamt with its new Luft-Post service. The Luft-Post allows the transfer of letters and packages across the nation and to countries of: Switzerland, Luxembourg, Austria-Hungary (Austria Proper and Bohemia-Moravia only), and Denmark via Pegasi. Their expertise in flight has put them at the forefront of aero development in Lighter-than-Air and Heavier-than-Air travel. Sizable Pegasi communities exist mainly in Southern Germany, with higher altitude settlements in Bavaria and Wurttemberg.

3732613 Good point there.