In 0 BBY, Imperial officers of the Galactic Empire wore insignia consisting of a confusing collection of multi-colored rank squares on the left breast of the officer’s uniform with a combination of several metal cylinders to either side of the rank badge. By the next few years, the rank squares had become a much simpler collection of red and blue squares with the code cylinders still in use.
In the Galactic Civil War, most Imperial officers were verbally addressed as ”Commander” with the exception ofAdmirals, such as Admiral Kendal Ozzel and Piett who were addressed as ”Admiral”. It should be noted that ”commander” is an acceptable form of address for captains, majors, colonels, or anyone of any rank who commands a military unit. Grand Moff Tarkin was referred to as ”Governor”. With such generic terms, the Star Wars films give little hint to a system of ranks and insignia. Over the years, however, the Expanded Universehas established a system of ranks and insignia which matches closely to the characters and the ranks and authority which they most likely held.