There are multiple artists/bands with this name:
1) A Swedish power-pop band
2) A Chinese hip-hop, jazz artist

1. Nom De Guerre describe themselves as a "A piano-pounding, bass fuzzing, drum-whacking power-pop trio." And for once, a band's description of themselves is not so far off base. "So Long Sister" features some great pounding piano and stirring bass. What they don't mention are great catchy vocals and a total pop sensibility which sees them writing a short, to the point, and hook laden song. This Swedish three piece certainly know how to write a catchy tune, and with this one, Hector, Louis and George have put together a brilliant song here and certainly deserve their name of war!
Matchbox Recordings

2. Nom De Guerre is a Chinese Hip-hop Artist that was born in ShenZhen China, and living in Atlanta, GA. Read more on Last.fm. User-contributed text is available under the Creative Commons By-SA License; additional terms may apply.