From the official site, here are some of the details.
With Milestone 1.12: Rebel Apostles we are introducing incentives for characters belonging to nations with the lowest populations on each server. We are hoping to point new players, and returning players who make new characters, towards those nations who need higher populations to compete in the conquest of the Caribbean.
These changes should help new and current players add to the strength of their nation, grow their economies, support their society structure and enhance their RvR efforts and participation.
The first change you will notice is that character creation will automatically default to the nation most needing new recruits for that specific server. The nation selection is not locked, however; you can still choose other to play other nations. We’ll continue to monitor population numbers and adjust which nations get this special status as time goes on.
If a player does choose one of the high population nations in character creation, a window will appear indicating that lower populated nations are seeking aid. The server Message of the Day will also list the lower populated nations and the incentives that players of those nations will receive.
Incentives
All characters of low population nations will receive:
- An XP bonus (double the usual rate).
- A 30% chance at a bonus loot reroll.
Below is a list nations that will receive incentives for each server. Default character creation nations are italicized:
- Antigua – Spain and France
- Defiant – All Nations (Spain will receive default character generation)
- Blackbeard – France and Spain
- Rackham – France and Spain
- Roberts – Spain and France
source: Offical Site
