Battle of the Rebels is the unofficial name of a storyline goal which is triggered as a random travelling event. When the first goal is finished and Leandra is a known rebel as well (quest does not have to be completed yet), it can be iniated by travelling near the road.
In the jungle, the two rebel groups are fighting against another and the player character happens to witness the battle. The player can decide to join the fray immediately, wait until one of the groups is victorious or withdraw.
Joining the fray
In case you join the fray, you have to fight twelve enemies. Their are two groups of six rebels and these groups will only attack you and no rebels from the other group, so it will be a hard battle to win.
Attacking the defeaten rebels
In case the surviving members of Esteban's rebel group are attacked, the player has to defeat eight opponents, which are one scout and warrior, a veteran and recruit trapper, two man-at-arms soldiers and one doctor and hunter who are recruits.
Depending on the made decision, the accessable terrain and starting positions are slightly different, but the amount of enemies and the troops don't change. If the opportunity arises, take down the veteran trapper, who poses the biggest threat with the hailstorm ability.