Commander Branko was in charge of the forces occupying the planet Olkarion. He hoped that by forcing the Olkari engineers to build him a massive, cube-shaped superweapon capable of mimicking any attack, he could earn back a position with Zarkon's main fleet.
Team Voltron and Ryner's forces thwarted that plan, however, and ultimately drove the Galra forces to flee the planet.
Branko returned to lay siege on Olkarion following Zarkon's death by unleashing an Olkari-made weapon that infected the forest and turned it against the Olkari. Thanks to it, he was almost able to capture Voltron, but Voltron broke free and the Olkari's ion cannon subsequently destroyed his ship.
“After the cube destroys Olkarion, hopefully Zarkon will welcome us back to the main fleet.” - Commander in "Greening the Cube"
- One wonders why he thinks Zarkon would welcome him back, as the Emperor has already demonstrated one chance is pretty much all you get in the Galra empire.
- Particularly since destroying - and thus wasting - an entire planet's Quintessence as well as its highly valuable slave labor force doesn't exactly demonstrate your competency.