Not guessing, but that vignette is glorious.

The flag of the lion of St Mark in particular.
Thankyou. Very good of you to say so

.
Keep those guesses coming.....
OK, here's a clue, it features a vignette of Francesco Gonzaga Crossing the River Taro at the battle of Fornovo that I did for a demo game that I have planned of the said battle:

Keep those guesses coming.....
Cheers,
Darrell.