Diplomatic Actions
Diplomatic Actions are how every act of diplomacy in Imperium Sine Fine actually happens — there's no menu of instant decisions, only actions that take real time to complete, cost Imperial Influence to begin, and can be interrupted.
How Diplomatic Actions Work
Only one diplomatic action can be in progress at a time per empire. Starting a new one cancels whatever progress had been made on the previous one entirely — there's no banking partial progress for later.
Every action costs Imperial Influence, deducted the moment the action's timer first begins ticking. If you can't afford an action, its button simply doesn't appear at all — there's no way to start something you can't pay for. While a diplomatic action is in progress, your empire's research is paused (though no progress is lost) — the same trade-off a settlement makes when running any other project instead of its default ongoing Expansion (see Projects).
Some actions complete instantly upon finishing. Others — offering peace, proposing an alliance, opening borders — instead create a diplomatic request for the receiving empire, which they can accept, decline, or simply ignore. A request stays open for a limited number of cycles; if it's never answered, the empire that sent it gains an Ignored relation penalty against the recipient. See Relation Values for what that actually costs you.
Quick Reference
| Action | Requires Translation? | Imperial Influence Cost | Time |
|---|---|---|---|
| Break Treaty | Yes | 25 | 120 cycles |
| Declare Friendship | Yes | 10 | 60 cycles |
| Declare War | No | 50 | 180 cycles |
| Insult | Yes | 10 | 30 cycles |
| Offer Peace (War → Neutral) | No | 20 | 60 cycles |
| Offer Peace (Neutral → Peace) | Yes | 20 | 60 cycles |
| Open Borders | Yes | 15 | 60 cycles |
| Open Communications | No | 10 | 60 cycles |
| Propose Alliance | Yes | 30 | 120 cycles |
| Send Large Gift | Yes | 5 | 90 cycles |
| Send Small Gift | Yes | 2 | 45 cycles |
| Join Wars | Yes | 25 | 90 cycles |
| Return Cities | Yes | 30 | 120 cycles |
Open Communications
The very first action available between two empires that don't yet understand each other, and the only one that explicitly requires no translation to begin — its entire purpose is establishing it. Once complete, both empires gain full mutual translation, opening up every other diplomatic action between them. See Languages and Translation for why this matters so much before anything else becomes possible.
Declare War
Moves the treaty status to War immediately upon completion — and drags every ally of the target empire into that same war too. Declaring War is the one action that never requires translation, reflecting that no shared language is needed to make your hostility understood.
There's a cooldown worth knowing: two empires that have just ended a war must wait 720 cycles (6 months) before either side can declare war on the other again. The relevant button simply won't appear until that cooldown has passed.
Break Treaty
Steps a treaty back down one level — Alliance becomes Peace, and both Peace and Peace with Open Borders become Neutral. The target empire is only informed of the new diplomatic status; no explanation is given, and none is expected. See Treaty Types for the full ladder this moves you down.
Offer Peace
The same action serves two different purposes depending on the treaty status it's starting from, with different translation requirements for each:
- From War to Neutral — uniquely requires no translation. This is the second exception (alongside Declare War) to the rule that diplomacy needs a shared language first — you don't need to understand someone to stop attacking them.
- From Neutral to Peace — requires translation, and creates a diplomatic request the target must actually accept for the new status to take effect.
Open Borders
Available only once two empires are already at Peace, this creates a diplomatic request to upgrade the relationship to Peace with Open Borders — granting free movement through each other's unoccupied territory. See Treaty Types for exactly what that freedom does and doesn't permit.
Propose Alliance
Available once two empires hold Peace or Peace with Open Borders, this creates a request to form a full Alliance — the strongest treaty type in the game, carrying mutual defence obligations and shared visibility of each other's assets. See Treaty Types for the full detail on what an alliance actually commits both sides to.
Declare Friendship
A goodwill gesture that grants the target empire a temporary positive relation modifier towards you — useful groundwork before attempting to upgrade a treaty, since several requests are easier to land with a healthier relation value behind them. The target is informed only that the action took place. See Relation Values for how the Friendship modifier itself behaves and fades over time.
Insult
The deliberate opposite of Declare Friendship — available while at War or Neutral, this applies a negative relation modifier against the target. There's rarely a strategic reason to use this against someone you might want to deal with later, but it exists as a genuine option, not just a flavour action.
Send Small Gift / Send Large Gift
Both gift actions transfer a portion of your own stored equipment to the target empire — 25% for a Small Gift, 50% for a Large Gift — and both require holding at least 100 units of at least two equipment types before the action can even be started, so an empire can't gift away equipment it doesn't genuinely have to spare. Like Declare Friendship, gifts apply a positive relation modifier, and the target is informed only that a gift was received.
Given the steep difference in what's actually handed over, a Large Gift is a genuinely costly gesture — not something to send lightly to an empire you're not seriously trying to win over.
Join Wars
Available only while in Alliance, this lets your empire take an active role in a war your ally is already fighting, rather than standing aside as alliances do by default. There's no invitation required from the ally — it's entirely your own empire's choice to formally commit. Once complete, your treaty status changes to War against every enemy your ally is currently fighting, and your ally gains a positive relation modifier towards you for the support. See Treaty Types for why an alliance doesn't drag you into a war automatically in the first place.
Return Cities
Available while at Peace, Peace with Open Borders, or Alliance, and only if your empire currently controls one or more cities that were originally founded by the target empire. Completing this action hands every such city back to its original founder, and grants the target empire two separate positive relation modifiers — one specifically for the act of returning their cities, and a broader one for trustworthiness in general. Both empires receive a report for every city involved in the transfer.
This action also requires your own empire not be involved in any wars of its own at the time — a genuine gesture of goodwill isn't something attempted in the middle of a crisis elsewhere.
