Captain of the Line
From Wookieepedia, the Star Wars wiki.
The position of Captain of the Line, was a military rank in the Imperial Navy. A Captain of the Line typically commanded a tactical unit known as a line of battle, comprising between five and twenty corvettes, frigates or cruisers. Officers of the same rank could often command a single Star Destroyer, or serve as the adjutant to an Admiral.
In terms of the Navy's rank hierarchy, the responsibilities of a Captain of the Line seem broadly similar to those of Commanders such as Pter Thanas, Kratas, and Ait Convarion; but it seems likely that the two ranks were distinct, inasmuch as Commanders were senior to all officers holding a rank of Captain. The rank of Captain of the Line was thus probably broadly analogous to that of Captain in many other space fleets, although there may have also been subordinate grades of Captain in the Imperial rank structure.
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In the real world, the nearest parallels to "Captain of the Line" are ranks such as the historical Austro-Hungarian Linienschiffkapitan, which indicated the command of a single ship of the line, rather than a full line of battle.
At the influential Star Wars Technical Commentaries fan website, this rank is cited as Line Captain, [1] and in the same site's page on Imperial insignia, two rank badges are identified as appropriate for the position. The first of these consists of four red above four blue squares, with two code cylinders in either shoulder pocket, an insignia not seen in the movies, but apparently worn by an Imperial mission commander in the video game TIE Fighter. The second insignia is a row of yellow rank squares with a single code cylinder in either pocket, as worn by Captain Khurgee aboard the Death Star.
However, it appears that there is no canon support for referring to this rank as "Line Captain" rather than "Captain of the Line", and the suggested rank-badge insignia are certainly fanon, unofficial and hypothetical suggestions. There is no canon evidence to confirm that either of these insignia indicates a Captain of the Line, and it might be doubted whether Khurgee holds such a relatively senior rank. The Wizards of the Coast card game uses an image of him to depict a Helmsman, although it is unclear how this title should be reconciled with the older Decipher card game's identification of him as a docking-bay security officer, which is, essentially, the role that he performs in the movie.
