And when they were up, they were up,
And when they were down, they were down,
And when they were only half-way up,
They were neither up nor down.
The duke in question was possibly Frederick, second son of George the Third (1763–1827), and rather a good man to have on hand if you were a soldier. He was responsible for the administrative overhaul of the British Army that was instrumental in defeating Napoleon on the Spanish Peninsula and Waterloo.