"This Is Why We Fight" is the sixteenth episode of the ninth season of Grey's Anatomy and the 188th produced episode of the series. It is also the 299th produced episode of the Grey's Anatomy franchise. It was broadcast on February 21, 2013.
The crash survivors race against the clock to try and find a buyer for Seattle Grace Mercy West while, in the wake of the mass walkout, tensions mount among the hospital's remaining staff while Owen looks to Cahill for support as they try to get the deal with Pegasus on the table, but Owen remains unaware of Cahill's real intentions. Meanwhile, Catherine urges Jackson to leave Seattle and return to Boston to join her practice while Bailey also finds herself questioning her future career prospects. Richard begins to question if there was a greater purpose for the survivor's walkout while Alex and Jo treat a young patient with a tumour.
- "There is a procedure to treat epilepsy that involves surgically severing the connection between the left and right brain. The goal is to block signals that cause seizures. The problem is this also cuts off the brain's ability to communicate with itself. The left side has no idea what the right side is up to. Patients may experience problems with co-ordination, memory, speech. It's a drastic solution that's only considered when all other options have failed because once a surgeon makes that cut there's no going back."
- "There's a reason surgeons are willing to roll the dice on a risky, go for broke, point of no return surgery with potentially devastating consequences. Sometimes it works."
- "Never Gonna Let You Go" - Esthero
- "Salty Sweet" - Ms Mr
- "Bones" - Ms Mr
- "Mountains" - Kris Orlowski & Andrew Joslyn
- "What I Wouldn't Do" - Serena Ryder
This episode's title originated from the song This Is Why We Fight, originally sung by The Decemberists.