A study of 186 hunter-gatherer cultures found that when men are involved in the care of their own infants the cultures do not make war.
This greater involvement of men with their babies may eventually contribute to a more peaceful world. It would, if true of “advanced” nations, be very much in the spirit of Epicureanism.
In a country like the US, this wouldn’t have much of an effect because wars are only fought by a professional armed service. Thanks vast majority of people will never fight at all. The only difference it would make is to less advanced societies in Africa and the Middle East, where having a professional army and defending yourself requires a substantial proportion of the male population. But these are also the most patriarchal societies, where this is least likely to happen.