The Veterans Day that Americans observe this week is rooted in hopes for peace that burst in 1918 from a train parked in a French forest: Allied and German military officers had signed a halt to humanity’s deadliest war ever. One hundred five years later, warfare in Ukraine, Israel-Gaza and dozens of countries have heightened both bloodshed and Americans’ concerns about whether humankind can fulfill our hopes for a world governed through laws rather than armed might. Still, the building of peace continues, even amid violence — and its builders include those who know best the horror of wars for having fought them.