The Noble Duke of York Song: Version 3

The video tutorial narrates the story of the Duke of York and his 10,000 men marching up and down a hill. It explains the different states of marching: being up, down, or halfway. The tutorial emphasizes the repetitive nature of the march and its significance through a song.

What is the significance of the phrase 'Let's March up and down and sing it again'?

Summarize the overall theme of the text regarding the Duke of York.