Many factors influence whether you hit your opponent or not. Your and your opponent's skills are important, but also your position, distance and a bit of luck.
Only the following skills are important in the battle for the fort:
Leadership is taken into account when shooting, as well as when dodging a shot. It also gives a damage bonus.
Aiming is only taken into account when shooting at someone.
Dodge is only taken into account when we try to avoid being shot.
Hiding is a consideration for attackers when they are trying to shoot or avoid being shot.
Setting traps is a consideration for defenders when trying to shoot or avoid being shot.
Health points are taken into account when determining a character's health points.