- If you are looking for the episodes of this name, they are
located at "Chain of Command, Part I" and "Chain of Command,
Part II". The chain of command was a ranking system used by
militaries and other organized groups. It represented the line
of authority down which orders are passed from one officer to
another, and also the line down which passed command of a
particular vessel or installation. Aboard a starship, or most
starbases the chain of command began with the assigned
commanding officer, usually an officer of the rank of captain,
or in some cases commander. If the commanding officer, for any
reason, was unavailable to command his or her post then those
responsibilities passed down the "chain" to the first officer,
then the second officer, etc. Between the launch of the
Enterprise NX-01 and the late 23rd century, the position of
first officer, or executive officer (abbreviated as XO) was
filled by the highest ranking officer assigned to the ship aside
from the captain. The position was not a separate