Are there any scriptures discussing on how to prevent wars? I mean for example, from the insights of scriptures, if Buddha were alive then how would Buddha have tried to stop World War 2?
There has been a debate among monks on the relationship to war that a Buddhist must have.
- War and Peace: A Buddhist Perspective By Bhikkhu Bodhi
- Thanissaro Bhikkhu's rebukes of Bhikkhu Bodhi's advocacy for a Buddhist doctrine of Just War
I advise you to read it.
The two monks explicitly discuss what a Buddhist should have done during WWII, and the Buddha's position on the subject.
There's a description of that here: Why Was the Sakyan Republic Destroyed?
I think the article is based on the canon, but I've forgotten where in the canon I read of it.
Anyway to quote from the article:
When the Buddha learned about this outbreak of hostility, he came there himself. On seeing this revered and eminent person from their royal clan, the warriors of both sides became deeply embarrassed. All of them laid down their weapons and paid homage to him. This was the traditional way of paying respects to the Buddha in those days.
Whenever King Pasenadi of Kosala went to pay respects to the Buddha, he would leave the royal insignia such as his sword, turban, fan, parasol and sandals outside with his attendant before entering the chamber of the Buddha.
The Buddha took the seat prepared for him on the open ground of the riverbank. The Sakyans and the Koliyans paid homage to the Buddha and sat respectfully on one side before him. The Buddha explained to them that their blood was much more valuable than the river-water. They should not spill blood unnecessarily. Instead, they should find a way to share the water peacefully. The Buddha was a peacemaker filled with compassion. He did not consider it proper that human life should be lost for the sake of trivial material gains.
And it goes on -- you can read the article for more.
The eventual outcome was that the Sakyan clan was massacred.
War is usually caused by some sort of conflict.
And conflict is caused by taking sides, "us" vs "them".
And taking sides mostly happens due to attachment to some concept or generalization for example:
- only this is right, everything else is wrong.
- only this is good, everything else is bad.
- this is ours, it belongs only to us.
- this is how it's always been, it must continue to be this way.
And so on.
So the Buddhist way to prevent war is to explain the dangers of limited thinking and promote the virtue of enlightened mindset that does not take sides based on generalizations.
Take a look at this web site, which addresses this very subject. (I have no connection with the site or its owners.)
Being selfless per Buddha's teaching according to Master Junhong LU from Guan Yin Citta he established aiming to help people for free while being awarded with ambassador for world peace can help dissolve the war.
What do people or countries fighting for? Nothing but Fame, materials or say greedy, hatred, ignorance. All because there is a "self" not "others". In many lifetimes, Buddha had been cultivating giving such as treasures he had, wives, sons, bodies and the countries, so there had no wars and he ended reborn in heavenly realms.