What leads to war most of all is the difference between populations of countries with different political systems. Knowing the other person's language and being able to communicate with "the enemy" would certainly reduce the incidence of political conflicts leading to violence. French is a language that is spoken not only in France but in many other countries of our world and should be taught in English-speaking countries from Kindergarten on so that our future populations can understand each other. It would also be to the advantage of everyone if other languages, especially languages like Japanese, Russian and Chinese were taught along with French.
Don`t force the language on people who don`t want to learn it.. If people are forced to learn it, especially at a young age, then they will potentially hold grudges against the language later in life. Forcing a language down people`s throats is not the answer...The exception to this rule is english because it is one of the most common languages in the world.
Except in countries surrounding France and other French-speaking places, French should definitely not be required. If any language should be required as a second tongue, it should be English as this is the most widely used language in the world, especially in international and business relations. Knowing English is the most practical of all languages for this reason.