So you need to send someone to conduct diplomacy on your behalf. Whom do you send?
Generally speaking, you have to balance two considerations: capability and prestige. An ignorant diplomat who knows nothing about the country they’re sent to, the priorities of your own government, or the delicate arts of interpersonal and international conduct can be anything from useless to incredibly damaging . . . but then, so can a diplomat who has skill but no status beyond what you’ve given them. Sending a low-ranking nobody, no matter how talented, risks giving insult to the host, especially in an aristocratic society. Even in modern democracies, the ambassadors to friendly countries may be distinguished more by their wealth and political connections than by any other qualification; the load-bearing work of the embassy can be delegated to underlings.
Who you send, though, also depends on how much authority you intend to give to your representative. (There are a lot of possible terms for that representative — diplomat, ambassador, envoy, legate, emissary, nuncio — but we don’t need to split definitional hairs here.) At the extremely limited end, the person you choose might simply be a messenger, carrying written or verbal correspondence between you and your fellow ruler. In that scenario, they have no power to negotiate . . . and they could get into a great deal of trouble if, upon being questioned by your neighbor, they open their mouth and say something you haven’t authorized.
But that’s an inefficient method, especially when the travel time is long. Instead, diplomats commonly have some amount of leeway to negotiate the terms of the deal — whether that’s about lifting tariffs or choosing a royal bride — still communicating back home for approval of specific points or the final agreement, but not slamming to a halt every single time a new question arises. At the extremely broad end, the diplomat is fully empowered to deal on behalf of their sovereign, with no need to refer back. I haven’t read it yet, but Theresa Earenfight’s The King’s Other Body discusses the period where Aragonese queens were, as the title suggests, seen as literally being the king for certain purposes: their presence was the king’s presence, and anything they said within that context was treated as the king’s word.
You may also be sending a diplomat for one, limited job, and after that they come home, or you may be sending them for long-term work. A resident ambassador can spend years in the country of their posting, using messengers to communicate back home as needed. This can become a double-edged sword: they’ll grow very familiar with the players and power dynamics of that foreign government — which is useful — but it comes at the cost of losing touch with the politics back home. In a worst-case scenario, their loyalties might wind up in the wrong place. Some countries have preferred to cycle ambassadors out on a regular schedule so as to avoid that problem, despite losing some of the deep institutional expertise they could otherwise acquire.
As you can imagine, any delegation of power risks going badly. If you choose an inept diplomat, you may find yourself saddled with deals that don’t favor you, or giving offense where you were hoping to achieve amity. Disavowing your diplomat and any agreement they’ve worked out (or insult they’ve offered) doesn’t really solve things, either, since that makes you look weak — after all, you chose this person! — and undercuts the entire notion of diplomats being able to act on your behalf. Of course that still happens; sometimes looking weak is better than accepting a bad bargain. Then the diplomat might have to choose between going home and facing the consequences, or pleading for sanctuary where they are. If the host country doesn’t want the trouble of harboring the personal enemy of a neighboring ruler, the diplomat could wind up completely homeless, looking for a country willing to take them in.
Conversely, trouble might arise at their place of posting. When relations break down, what happens to the diplomat? Nowadays we have the official concept of “diplomatic immunity,” meaning that such individuals are not subject to local laws and control: they are free to enter and leave the country, can’t be prosecuted for most crimes, etc. The basic principle is an ancient one, because it’s hard to conduct any kind of diplomacy if messengers can’t go safely back and forth; around the world, you find the notion that such people should have a protected status.
But protection isn’t true, unbreakable immunity, even under modern law. When things go south, diplomats may be imprisoned, tortured, or even executed. Sometimes there’s a legal justification for this — e.g. they were spying or inciting loyal subjects to treason, or the individual they serve is officially a “rebellious subject” rather than the sovereign of a separate land — or the government that sent them disavows them and revokes immunity. Sometimes it’s just the host country throwing diplomacy out the window and declaring war. On other occasions, something bad happens to the diplomat, and even though it’s genuinely an accident or illness, not local malfeasance, whoever sent the diplomat believes (or chooses to believe) that it’s deliberate provocation.
Diplomatic relations nowadays are complex enough that they tend to involve full-time missions with a host of support staff. As such, they’re housed in their own building — sometimes several buildings, e.g. separating the ambassador’s residence from their offices. These locations are usually not “foreign soil,” though that’s a common belief; while some embassies are literally extraterritorial enclaves within another country’s borders, that’s an exception rather than a rule. They just enjoy certain protections, much like the diplomats do, which can make them places of legal refuge for foreign nationals or locals seeking asylum. That latter, though, can become a diplomatic flash-point of its own: are you willing to risk angering another country by giving shelter to their enemies? In such instances, especially before the ability to get on the phone and call someone for immediate approval, the diplomat is put in a very tense position. The decision they make in the moment could have repercussions for years to come.
All the more reason to choose carefully in deciding who to send. But, well, this series is written with writers in mind . . . and for us, the bad decision is often the more interesting one! The inept envoy, the ambassador with questionable loyalties, the inexperienced courtier sent to a posting that should have been quiet but suddenly ignites into a hot zone of conflict over one minor incident — all these things and more are potential fodder for stories.