Post "The Great Game" fic

[donutsweeper.livejournal.com]

I'm looking for a shortish fic that is set right after "The Great Game" where Sherlock has been hurt and John is trapped in a flashback and thinks he's still a soldier. He manages to call Lestrade, but is using Army terms for things and uses his phone like it's a radio. I think he's also got a gun and mistakes the police for insurgents and threatens them with it.

Anyone know what story this is? Thanks in advance!

Found by travels_in_time almost immediately: Cadence to Arms, by mad_maudlin