The trooper
Post 473 was a designation given to a clone trooper that was assigned with destroying a bridge in order to prevent a Separatist droid army from conquering a mining colony on a planet.
Behind the scenes
The Post 473 designation first appeared in the short story Waiting, which was one of four stories in the tenth volume of the Star Wars: Clone Wars Adventures trade paperbacks. It was created by Matthew and Shawn Fillbach.
Appearances
"Waiting" — Star Wars: Clone Wars Adventures Volume 10 (First appearance)