CurseForge · Minecraft mod
Casus Belli
Diplomacy and politics for roleplay servers. Create your own empires, ally with them, go to war, and negotiate your way back out. Inside each one there are parties, elections and a senate that votes on laws.
Quick answer
Which Casus Belli release should I use?
Casus Belli casusbelli-1.21.1-1.0.0.jar targets 1.21.1 with NeoForge. The project page does not say whether this file belongs on the client, dedicated server, or both. No extra mods listed for this file.
Where it goes
Is Casus Belli required on the client, server, or both?
The project page does not say whether this file belongs on the client, dedicated server, or both.
The source does not explicitly classify this release as client-only or server-only.
What else does Casus Belli casusbelli-1.21.1-1.0.0.jar need?
casusbelli-1.21.1-1.0.0.jar. Change the file and its required mods may change too.
This file does not list any required mods. Do not add a library just because a different file uses it.
This file does not list any required or optional mods.
Before you install it
Add Casus Belli without breaking your instance.
Built for Casus Belli casusbelli-1.21.1-1.0.0.jar. Pick another file and the loader, install side or required mods may change.
- 01
Stick to this file
Use casusbelli-1.21.1-1.0.0.jar. It targets 1.21.1 with NeoForge; another release may have different loader, side or dependency requirements.
- 02
Bring the mods it needs
This file does not list any required mods. Do not add a library just because a different file uses it.
- 03
Put it on the correct side
The project page does not say whether this file belongs on the client, dedicated server, or both.
- 04
Pick the file you checked
Use the “Get this file” button beside casusbelli-1.21.1-1.0.0.jar. It opens that exact file at the source.
About this project
What does Casus Belli add?
Casus Belli
Casus Belli is a politics and diplomacy mod built around player-run empires.
Create or join an empire, form political parties, win elections, pass laws through the senate, make alliances and negotiate with other nations — or lead your empire into war.
Features
Custom Empires — Create empires with their own name, tag and colour.
Diplomacy System — Relations progress from Peace → Tension → Imminent War → War.
Alliances — Form alliances, answer calls to arms and choose who you support.
Wars & Peace Treaties — Declare wars and negotiate treaties involving every nation in the conflict.
Political Parties — Create parties with their own ideology, colour and leadership.
Elections — Governments are elected for limited terms.
Senate & Laws — Players can propose and vote on laws.
Reputation — Political actions affect how easy it is for a government to pass legislation.
Autocracy & Censure — Powerful governments can become autocratic, while opponents can attempt to remove them.
Historical Records — Wars, alliances, treaties, elections and major political events are recorded automatically.
Most features are available through in-game menus:
G — Empires, diplomacy and alliances
L — Senate and laws
P — Parties, elections and parliament
Casus Belli is highly configurable through config/casusbelli-server.toml: diplomacy rules, reputation values and permissions.
Languages: English and European Portuguese.
Discord: https://discord.gg/WREpYVff
Project description from CurseForge.
Pick your setup
Casus Belli by Minecraft version and loader
Choose the version and loader you play, then open the matching release.
Check the dependencies, then try the file in a copied instance before changing a world you care about.
Recent files
Casus Belli versions and loaders
casusbelli-1.21.1-1.0.0.jar
26 Aug 2026
Looking for an older file? The official CurseForge project page is in Resources.