1. Upgrade the officers to improve the Leadership of officers and their Special Operation Squad stats.
The number of troops which an officer can lead in Battlefield Expedition grows with the improvement of the officer's Leadership.
DPS and HP of Special Operation Squad directly influence its Power.
In addition, officer needs to reach certain level before they could be promoted.
1 Star Officer's Max Level: Lv. 10
2 Stars Officer's Max Level: Lv. 25
3 Stars Officer's Max Level: Lv. 40
4 Stars Officer's Max Level: Lv. 60
2. Promote the officer to unlock more officer skills.
When an officer has reached the max level of a star-level, you can promote the officer to gain more stars and unlock higher max level and more skills.
Only the unlocked skills are able to take effect under specific situations.
1-star officer can be promoted to 2-star when reaching Lv. 10.
2-star officer can be promoted to 3-star when reaching Lv. 25.
3-star officer can be promoted to 4-star when reaching Lv. 40.
3. Upgrade Officer Rank to improve officer's skill stats.
Officer's level and star don't have any influence on the upgrade of officer's rank.
Whenever officer's skill is unlocked, officer's rank is the only factor influencing the skill stats.
Officer's top rank is 12.