Q:

Meaning of "With Ismail's storm to soften it the more" in Byron's "Don Juan"

Canto 8, stanza 68, from Byron's Don Juan: 

So much for Nature: -- by way of variety,
  Now back to thy great joys, Civilisation!
  And the sweet consequence of large society,
  War, pestilence, the despot's desolation,
  The kingly scourge, the lust of notoriety,
  The millions slain by soldiers for their ration,
  The scenes like Catherine's boudoir at threescore,
  With Ismail's storm to soften it the more.  

What is the meaning of it in the final line of the stanza? The boudoir? What does it mean then, "to soften the boudoir"? 

A:

‘Catherine’ is empress Catherine II ‘the Great’ of Russia, and in the poem she has taken Don Juan as her lover and protégé, as she did Grigory Potemkin, Grigory Orlov, and others in reality.
‘It’ refers to the boudoir, but by metonymy ‘boudoir’ refers to Catherine herself. This is clear from ‘at threescore’: the empress was 61 years old in 1790. So Byron is using ‘soften’ with this meaning (sense 6 in the OED):

To make (a person) more sympathetic, gentle, lenient, or emotional.

‘Ismail’s storm’ refers to the the capture of the fortified city of Izmail from the Ottoman Empire. This city, on the lower reaches of the Danube, was besieged early in 1790 by Russian forces commanded by Alexander Suvorov, and stormed on 22 December. The victory and the southern extension of her empire must have pleased Catherine, and made her better disposed to reward her favourites.

