Hawaiian shirts, digital cameras and cell phones…
I think there are only two ways to really make war on war:
1. Keep your own nation from entering a war. Lay down in front of a tank if possible.
2. Send about 200,000 people trained in non-violent action, preferably little old ladies and guys in wheel chairs, into the middle of a war zone with Hawaiian shirts, digital cameras and cell phones.
Some people do a version of this as “peace hostages” in many conflicts but the numbers are usually very small. The wider progressive community doesn’t have the nerve.
Unless you are willing to risk your life, you can’t declare any real kind of war on war. Anything else is 99% wishful thinking.