Military ranks establish order, command, and discipline. They signify levels of authority, responsibility, and expertise.
Officer Ranks and Structure
Officer ranks are in three tiers: company, field, and general. Commissioned officers hold the highest ranks. The army unit commanded by a captain is the company.
Historical Perspective
Between the 17th and 18th centuries, colonels and captains held similar ranks though colonels later led more regiments while captains led companies.
Highest and Lowest Ranks
The highest rank is O-10, or "five-star general," symbolized by five stars. Only nine Americans ever held this rank, with Omar Bradley being the last in 1981. In the Commonwealth’s air force ranking system, the equivalent rank to brigadier general is group captain.
The lowest ranking officer is an Ensign, equivalent to a Second Lieutenant in the Navy. An Ensign is an officer rank given to graduates from the military academy who passed qualification tests and basic officer training.