Kings don't change diapers. They just don't. The queen does it or the maids do it... Someone does it because it has to get done but definitely it's not the king's job to do it.
But what if in order to go to war, a king had to have change diapers for a year?
In the case of defensive wars, the king isn't required to change diapers as this imposes unrealistic demands. You don't want to be in a situation where the kingdom can't defend itself because the king has only been changing diapers for 11 months, not the full twelve.
If the royal couple doesn't have a baby of their own to change, then an orphan baby will be found for the purpose.
If the king continuously changes diapers for three years, he may wage a offensive warfare any time after the 365th day.
Obviously, kings will want to work their way around this requirement because baby poop is disgusting and a meneal task generally covered by women. Assume traditional gender roles, pre-1500 Europe. For the sake of this question, there is no way around it and the requirement is absolute. I can think of lots of ways to get around this requirement and that's not the point of this question.
So, with this requirement in place, would a king be more or less likely to wage aggressive wars and why? Given the wide range in temperament of all kings, please consider the most common human male personality attributes.