Ship To Ship Combat / Music

• There was an infamous bit of Ship-to-Ship Combat in X Japan fandom that actually led to legal threats being made and a large swath of bandslash being deleted out of fear of the Fandom VIP making them. It started around 2008, when a rabid Yoshiki x Toshi shipper managed to acquire status with a then-official forum. The shipper didn't like anyone who shipped hide x Yoshiki, and went about issuing legal threats to (and having her friend who was The Cracker hack) several well-known hide x Yoshiki writers. Most writers of the pairing deleted their fics or apologized or went underground at the time - the result being the deletion of almost all extant Yoshiki x hide or hide x Yoshiki slash at the time, unless the writers didn't care about the possibility of legal action, angry enough to ignore it. Eventually, the Flame War and the threats calmed down due to a variety of factors (the BNF losing official status, Yoshiki being far more open about his love for hide to the point where it became as close to canon as Real Life gets, hide fans and Toshi fans no longer being in open combat due to the events of 2010).
• The Vocaloids are a strange example of this, despite the fact that the canon changes with each song. Although there's no canon source to determine who should be paired with who, or who plays who for that matter (some songs even use Vocaloid characters to portray historical/mythological figures), this has not stopped Vocaloid fans from arguing with each other over this subject, the most visible of the bunch being KaitoxMeiko vs. KaitoxMiku and RinxLen vs. Everyone Else.
• In-Universe Example: Not Literally Productions' Filk Song "I Love It" is a shipper's anthem. In the chorus, the singer say she's more than happy to start a shipping war.
  Let's start a shipping war, don't care if I get hate.