The music playing is the 1812 Overture written by Russian composer Tchaikovsky.

It was written to commemorate Russia's successful defence against French invasion in 1812.

The year 1812 saw another war as well, that of the USA against the UK, when the USA declared war on Britain on 18 June 1812.

On a personal note, Tchaikovsky is one of my favourite classical music composers.

Edited to add:

Interesting to note, the original score has cannon fire at about the 31 second mark of the linked video. Yes, the sound of cannons firing was written into the original score.

The music in the video doesn't have that cannon fire. That cannon fire is one of the most iconic parts of that piece of music. I'm a percussionist and play in Orchestra's, I can tell you that no recording of that piece of music would exclude the cannons. It's that important to the piece of music (and incredibly fun to play as a percussionist, I have played a cannon as a musical instrument).

1812 Overture, war declared between USA and UK in 1812, no cannon fire in this version of the music. War without guns.

The music playing is the 1812 Overture written by Russian composer Tchaikovsky.

It was written to commemorate Russia's successful defence against French invasion in 1812.

The year 1812 saw another war as well, that of the USA against the UK, when the USA declared war on Britain on 18 June 1812.

On a personal note, Tchaikovsky is one of my favourite classical music composers.