Googling I am coming up with “the king’s final argument”.

The idea is the same. At some point, the conversation ends and the kings speak to each other with cannon balls.

Recall the scene in Henry V, which I watched again recently, where the Dauphin of France mocks Henry V, by sending him a bunch of tennis balls:

And tell the pleasant prince this mock of his
Hath turned his balls to gun-stones, and his soul
Shall stand sore chargèd for the wasteful vengeance
That shall fly with them; for many a thousand widows
Shall this his mock mock out of their dear husbands,
Mock mothers from their sons, mock castles down,
And some are yet ungotten and unborn
That shall have cause to curse the Dauphin’s scorn.

Henry was early enough that he mostly spoke with cloth-yard shafts, and not so much with his artillery. Henry lived yet in the world of vulgar brawls.

It would take some time before highly dignified events employing lavish amounts of artillery could happen.

Frederick, from his balcony seat in Valhalla, must have enjoyed the exquisitely dignified artillery symphonies of the 20th century.