The nation with the most knights on the sea field is stated as the owner of the sea field.
If armies of other nations on the same field will attack or defend depends on the diplomatic state with the field owner.
QUOTE:
The chance to fight in the battle depends on the seafight setting of the army leader.
The chance is 93%, 65,5% or 38% increased by 1% for every army at this field.
The news are not up to date.
This should be right:
QUOTE:
The chance to fight in the battle depends on the seafight setting of the army leader.
The chance is 95%, 67,5% or 40%.
The second part "increased by 1% for every army at this field" was deleted.
http://ritterheere.de/component/option,com_fireboard/Itemid,181/func,view/id,458027/catid,2/limit,10/limitstart,120/
The fight chance is calculated separately for each army.
For example:
Nation A has one army on the sea field with 95% fight chance.
Nation B has two armies on the sea field, each with 40% fight chance.
If one of the armies from nation B flees ( each army with 60% flee chance ); and the other army from nation B and the army from Nation A stay on the battle field, then there will be a fight between one army from nation B and nation A.
If the army from nation A flees ( 5% flee chance ), then there will be no fight.