From where do we learn the value of peace?

Writing for the Jewish Press, Rabbi Moshe Meir Weiss refers to Avot in a piece ("Allergic to Fighting") that opens with the following words:

One of the most fundamental missions of a Torah Jew is encapsulated in the Rambam’s statement at the end of the Laws of Chanukah: “The entire Torah was given to promote peace in the world, as Scripture says, ‘Its ways are ways of sweetness and all its paths are paths of peace.’”

 This statement is remarkable coming from the Rambam, who was an expert on all 613 mitzvos. We also know the value of peace from Pirkei Avos, which teaches, “Hashem is pleased with anyone with whom people are pleased.” 

To my mind, and with due respect to the author, it is not easy to see how this mishnah (Avot 3:13) is where we learn the value of peace: this is not what it says; nor is it normally understood by the commentators as referring to peace. However, the rabbi is quite right to say that Avot teaches us how valuable peace is. A more explicit source would be, for example, Avot 1:18 ("The world endures on the basis of three things: truth, justice and peace").