This is a poem in classical form by an early 20th century Englishman, I think, Auden or Spender or someone like that. As I remember, it's triggered by thoughts on a battle depicted on a piece of Roman pottery, sort of like that famous Grecian urn.
It ends with the couplet:
Roman, you'll see your forum square no more.
What's there but this to say of any war?
Googling came up with this reference to "Vale from Carthage" by Peter Viereck -
Roman, my shipmate's dream walks hand in hand
With yours to night ('New York again' and 'Rome'),
Like widowed sisters bearing water home
On tired heads through hot Tunisian sand
In cool urns, and says, 'I understand.'
Roman, you'll see your Forum Square no more.
What's left but this to say of any war?