Diplomacy in a nutshell in Total War Saga Thrones of Britannia Total War Saga: Thrones of Britannia Guide & Tips

Diplomacy allows you to improve the strategic standing of your country. However, not all nations will accept your alliance - certainly not permanently. The diplomacy may help you consolidate power in the area, protect yourself from aggression and facilitate expansion of your country.

After opening the diplomacy tab, the main screen will switch to diplomacy view. Your kingdom will be highlighted and the provinces of other countries will be accordingly colored. That's an overview of your relations with other nations (1). Your country is yellow. Green means very friendly relations and red means hostility. You can select another kingdom to see what relations do they have with others and plan your expansion accordingly.

The lower panel shows the list of factions (2). You can sort the countries according to Strength, Regions, Treaties and Attitude (3). After selecting any faction, press (4) to switch to negotiations screen. It allows you to submit different requests and demands. After choosing any of these, you will see the probability of success at the bottom. If that's too low, you should make a better offer.

At the sides, you can see the portraits of the leaders. Each leader is described with a few stats (5). Some of them indicate greed, others tell you what kind of culture they hate, what's the opinion about them or how likely they are to keep their word. The Welsh, for example, will always have a hard time finding common language with the Anglo-Saxons (not only literally), and the Vikings will have a hard time allying with pretty much anyone from the British Isles. High influence and the fame can do wonders for you in negotiations with others.

A declaration of friendship is a great way of starting the relations off at the right foot.

Types of diplomatic actions:

1. Payments - these allow you to transfer money to add more incentive in negotiations. You can also demand a payment from somebody. Gift money to others to improve your relations;
2. Military alliances - either break or craft an alliance with others. If you're threatened by an invasion, you can try to find allies. The alliance works if someone attacks you or declares war on you. Being in alliance doesn't automatically include all sides in the war. Each faction can decide whether they want to observe the terms of the alliance each time - don't be surprised if somebody bails out in the critical moment.
3. Defensive alliances - works similarly to military alliance, but is effective only if you (your ally) are attacked; you don't have to participate in conflicts that were initiated by your defensive ally.
4. Join war against - this allows you to join a war between other kingdoms, as well as ask them to join your war. Sometimes you will need to convince them with cash or good relations.
5. Military access - allowance to cross borders without starting a conflict or damaging relations.
6. Declarations of friendship - that's going to be the most common agreement in the game. This doesn't imply anything and is only used to improve relations. Declaring a war on your friend damages your reputation.
7. Arrange a marriage - if the circumstances allow it (you or the other faction have a girl available for marriage and the other side has a young nobleman), you can arrange a marriage. This will significantly improve your relations.
8. Create vassal kingdom - this action lets you create a vassal state that will be under your reign - and hence your ally. Such country will not carry out external diplomacy, but can still cancel the agreement.
9. Annex - available for some countries. This allows you to peacefully take over the territory of another country and merge them into your own kingdom.
10. Peace treaty - only available during wartime. After settling the details of the treaty, you can end the war.

Note that diplomacy is most useful when it comes to securing your borders. The countries that are allied with you, or are otherwise bound to your country, are not keen on waging wars against you, at least not in the short run. It's a good idea to craft an alliance with those countries that separate you from bigger rivals. It's also viable when the move will make conquering somebody easier. Don't try to cheat the countries you want to conquer by forging alliances with them and then attacking - this damages your reputation, making it more difficult to successfully carry out any diplomatic task.