Just because you're forced to make an oath doesn't make you liable to respect it. Morally speaking, forced oaths are invalid.
Of course, good luck explaining that to a martial court. You know, there's a reason why all the countries developed the 'soldier' profession. Beyond their training, the reason why all the nations have armies is because they are composed of individuals who don't question motives.
Imagine a world where everyone uses his head. So many politicians, dictators, prophets and kings unemployed, many many wars avoided.
