It isn't enough to talk about peace. One must believe in it. And it isn't enough to believe in it. One must work at it.
- Eleanor Roosevelt
(15) Shun evil and do good; seek peace and pursue it.
(26) Then I sent messengers from the wilderness of Kedemoth to King Sihon of Heshbon with an offer of peace, as follows, (27) “Let me pass through your country. I will keep strictly to the highway, turning off neither to the right nor to the left. (28) What food I eat you will supply for money, and what water I drink you will furnish for money; just let me pass through— (29) as the descendants of Esau who dwell in Seir did for me, and the Moabites who dwell in Ar—that I may cross the Jordan into the land that the LORD our God is giving us.” (30) But King Sihon of Heshbon refused to let us pass through, because Adonai had stiffened his will and hardened his heart in order to deliver him into your power—as is now the case.
Then I send messengers from the wilderness of Kedemoth - Although the Omnipresent had not commanded me to proclaim peace unto Sihon, I learnt to do so from what happened in the wilderness of Sinai, i.e. from an incident that relates to the Torah which existed before (kedmah) the world. For when the Holy One, blessed be God, was about to give it (the Torah) to Israel, God took it round to Esau and Ishmael. It was manifest before God that they would not accept it, but yet God opened unto them with peace. Similarly I first approached Sihon with words of peace. — Another explanation: Moses said to God, "I learnt this from what you, who existed before (kedmah) the world, did to Egypt. You could have burned them up with one flash of lightening, but you sent me to tell Pharaoh "let my people go" (Exodus 5:1).
Ralbag - Rabbi Levi ben Gershon, France, 1280-1344
It is to inform us that one ought to pursue peace and keep controversy and war at a distance, even when it is clear that one would be victorious.
Rambam - Rabbi Moses ben Nahman, Spain/Israel, 1194-1270
Peace is great and controversy despicable. Peace is great, for even in time of war peace is necessary, as it is said: “When you approach a town to attack it, you shall offer it terms of peace” (Deut. 20:10), and “Then I sent messengers from the wilderness of Kedemoth to King Sihon of Heshbon with an offer of peace… “(Deut. 2:26).
One must love peace and pursue peace, as it is written: "Seek peace and pursue it." Seek it with your friend and pursue it with your enemy. Seek it in your place and pursue it in other places. Seek it with your body and pursue it with your money. [Sometimes one must be liberal with his money to seize upon the "stronghold of peace."] Seek it for yourself and pursue it for others. Seek it today and pursue it tomorrow. And do not despair, saying: "I will never achieve peace," but pursue it until you do achieve it. And what is the pursuit of peace? Thus have our sages of blessed memory said (Sanhedrin 110a): "This is speaking peace at a time of dispute and sacrificing one's honor for the general good, as was done by Moses, as it is written (Numbers 16:25): 'And Moses arose and he went to Dathan and Aviram…,'" and suspending one's affairs to make peace between a man and his wife, a man and his neighbor, and a teacher and his student — even to the extent of arranging a meal for two to make peace between them.