imperial radch - How are Radchaai ships and crews structured?

As I understand it, each Radch warship is one of three classes - a Sword, which is a rapid attack craft; a Mercy, which is some some sort of general-purpose in-between craft; or a Justice, which is a massive troop carrier designed to deploy hundreds or thousands of ancillaries. Though the three classes are established early in the series, the distinctions between these classes are not very explicitly described by the author. Still, it seems that, despite their disparate sizes, they have crews that are organized similarly, by "decades" of soldiers, each headed by a lieutenant who answers directly to the ship's captain.

How are these crews organized?

Answer

It seems that every ship's complement begins with two primary decades of soldiers:

• One decade is named after the ship's namesake (generally a patron god) and directly serves the captain (e.g. Breq's Kalr decade aboard Mercy of Kalr).


• One decade is named after Amaat, the primary Radchaai god, and that seems to be used to indicate the highest-ranking or most senior decade (aside from the captain's decade).

It also seems as if the decades below Amaat are assigned in pairs, named after the "emanations of Amaat". The final two decades stationed aboard Mercy of Kalr are Etrepa and Bo, after the "first emanation of Amaat", representing "light and darkness".

Aboard Justice of Toren during the Shis'urna annexation, the Toren, Amaat, Etrepa, Bo, and Esk decades were active, with Var decade and all below it inactive. Esk and Var are named after the emanation of Amaat representing "beginning and ending", and seem to be the next pair of names to be used after Etrepa/Bo. The Esk decade was stored on the level above the Var decade, and with Var level and below inactive, "half of (Justice of Toren's) decade decks" were "cold and empty". This indicates that a Justice is only designed to hold ten decades - presumably, that's one for the ship's namesake, one for Amaat, and one for each of Amaat's eight emanations.

The ten-decade complement, and other information alluded to in the novels, is confirmed by this infographic which Orbit Books provided to io9.com: (thanks to Matt Gutting for the link)

Each decade lieutenant commands at least one unit (but as many as five units) of ten or twenty soldiers or ancillaries. On larger ships, each decade has multiple units within it - Justice of Toren had twenty lieutenants in each decade, and the infographic indicates that this is common to Justice-class ships. Each group shares the decade name and is distinguished numerically. For instance, Lieutenant Awn commanded Justice of Toren One Esk, which was the most senior or highest-ranking Esk grouping. Each decade on a Justice has a Decade Commander who ranks above the lieutenants, and the captain of a Justice is known as the "Hundred Captain". The Hundred Captain's rank reflects her command over the ten decades of the ship.

So the crew complement of Justice of Toren, if fully staffed and with all ancillaries active, requires two hundred and eleven officers - twenty lieutenants in each of the ten decades, ten decade commanders, and a captain. Since each lieutenant can command as many as one hundred ancillaries (across five units), a Justice may carry up to twenty thousand troops. There are other personnel, such as medics, but their numbers are not described (and relatively few compared to the ancillary crew, which performs most maintenance and menial service).

While the crew of Justice of Toren is massive, we see that each of Mercy of Kalr's decades only has one lieutenant commanding a single unit of soldiers. Though Mercy of Kalr was shortstaffed before deploying with Breq as captain and other newly assigned personnel, the infographic informs us that this is the full complement of crew. The chart also confirms that each decade aboard a Mercy only contains ten soldiers or ancillaries, except for the captain's decade.

The infographic also shows us that a Sword carries six decades, with each (except the captain's) containing ten members, as on a Mercy.

In either case, each member of a decade is distinguished by a number - aboard Justice of Toren, decade members had designations such as "One Esk Nineteen", meaning Esk decade, first division, nineteenth member. Aboard Mercy of Kalr, each decade member is merely known by decade and their own number, such as "Kalr Twelve". Each ancillary or human decade member wears insignia on their uniform jacket indicating their decade and number. Within a decade of humans, the numbers indicate rank or seniority - while serving on Mercy of Kalr, Lieutenant Ekalu was promoted to Amaat One, and then to Lieutenant.