Sud el Bar was in Mesopotamia (modern day Iraq).WW1

According to Cathal O'Boyle's "Songs of the County Down", the song was written in 1919 by Canon Charles O Neill, a catholic parish priest in Down. The air "belonged to an old love song, recorded in 1913 by John McCormack". I'm not sure what that last refers to - although the air is certainly used (with slight differences) for "The Banks of the Moorlough Shore" - which is a beautiful love song!

"Brittania's sons" was definitely the original, BTW.

Regards