"I now find myself here, in this place, able to say only one thing: War is madness," Francis said. "Even today, after the second failure of another world war, perhaps one can speak of a third war, one fought piecemeal, with crimes, massacres, destruction."
The pope used his visit to the memorial - where 100,000 Italian soldiers killed in World War I are buried - to urge people to show more compassion for the suffering caused by current conflicts.
Francis has been urging an end to conflicts in the Middle East, Ukraine and elsewhere.
"From this place we remember all the victims of every war. Today, too, the victims are many," the pope said in his homily during a mass at the memorial, which commemorates soldiers that died fighting the Austro-Hungarian empire.
"With the heart of a son, a brother, a father, I ask each of you, indeed for all of us, to have a conversion of heart: to move on from 'What does it matter to me?', to tears: for each one of the fallen of this senseless massacre, for all the victims of the mindless wars, in every age," he said.
DPA