SOLVED. science fiction - military unit sent to another planet

[Bonhomous]

I have never read the books, but a friend said to me "I want to recommend this series, but I don't remember the author or the titles."
It's about a military unit who is sent by "Japanese overlords" to another planet to fight and they end up siding with the rebels.
The soldiers march to a song called the Whistling Pig.
Not a lot to go on, but any information would be appreciated.

[Bonhomous]

A Small Colonial War by Robert A. Frezza

https://www.goodreads.com/book/show/1...