Yeah, this is definitely not standard Gintama - but I can't help but crave some drama now and again. ^^; And the few fleeting references to the war always sound hellish, not a fun or funny time at all (which is probably why there's never been any extended flashback to it...) We know from what Otose's said that Gintoki was fairly broken from it for a long time after, anyway...

...oh, Gin-san, I'm sorry I love you (and your pain...)