Is there any fluff that looks at the Imperial Navy? I'm creating the backstory for my new Rogue Trader, and she is going to be a former Naval officer. I've written a lot about U.S. Navy ships from WWII for work, but I have little insight as to what individual officers might be in charge of aboard a ship.

What sort of responsibility would a second lieutenant have? A first lieutenant? Would a second lieutenant report directly to a first lieutenant? A first lieutenant to the lieutenant commander?

Not as important a question, but Rear Admiral is still a pretty important position, if not quite the commander of the entire fleet, right? (Not my character. Her father.)

How are the battlefleets named? Would she be serving in Battlefleet Calixis or Battlefleet Obscurus? Or do both exist?

Thanks in advance for your insight.

Both. Battlefleet Calixis is the battfleet of the Calixis sector, which is a part of Battlefleet Obscurous.

A Rear Admiral could command either a Battlegroup (formed from a fleet to pursue a particular objective or patrol a particular Sub-Sector such as Battlegroup Armageddon or Battlegroup Angevin) or part of one of those Battlegroup's (such as the Spinward Squadron of Battlefleet Angevin) or a major facility such as Port Wander (as the Port Admiral, with perhaps a Port Captain or Port Commander to assist them) or in a major branch of the Navy (such as Fleet Munitions Procurement Officer). Basically librally mx the Golden Age of Sail with a modern advanced Navy.

Check out the Battlefleet Gothic books for more information. Make for an interesting read. Steer clear of the novels though. They're contradictory enough to give you a head ache.

The Imperial Navy is hevely influenced by the British Royal Navy from somewhere between the 1600's to the late 1800's. Have a look there and then multiply everything you find by 11 and you should be doing fine ;-)

Black Library novel Relentless by Richard Williams should also point you into right direction.

Thanks for the reading recommendations!

Just to add (and at the risk of becoming tediously evangelical on the subject) that the writers of RT have repeatedly cited the Patrick O'Brien Aubrey/Maturin novels as a major influence on the tone and feel of RT. They are splendid books, set in the Napoleonic War era, and I cannot recommend them enough.

The Patrick O'Brien books are also great sources for Endeavour Inspiration.