(Op)that is a good question in my view,I would think they serve the Empire,cause the Empire seems to fund them,and I have been arrested by the Battlemages before.I think they are units in the Empire just like the Legion.

The college would be a branch of the Imperial Legion, I feel.

A battlemage is a Mage who specializes in War magic. They study the Art of War Magic. Some may heavy armors, some may wear lighter armor, but most wield blades and clubs and such.

However, their magical focus is in battle. Their spells are highly offensive in nature, heavily relying on Destructive magic. In Alteration their focus would be on shielding, and in Mysticism Reflecting spells. Restorative magicks would include absorption magic. They would use cursing spells of the nature like Burden, Weakness, etc. heavily.

Their offensive magicks would be combined with their skill with a blade for war effectiveness.

Seems like we also argue whether the Templars were loyal to the Church or themselves( if you follow)

I think we can safely assume the Battlemages are loyal to the empire just as the Mages Guild is( partly because the Empire funds them).

A good bit of the confusion seems to stem from the fact that we have never been properly shown the Imperial Bureaucracy (Its Boring)

It seems to me that that the best anology is probably modern Militaries, take the US Military for example:
Various groups, Marines, Air Force, Navy, Army, with different roles, uniforms and traditions.
But sharing a loosely integrated Bureaucracy, High level command staff and receiving orders from a civilian political Establishment
Some groups exist outside of this (Secret Service) but they still cooperate

It seems that Empire's Military has the Legion, the Battlemages, the Navy, and the Guard. With other groups (Blades) cooperating under
Civilian Imperial control. I also Imagine that local Militias would be anologous to the Nation Guard
I do however think that the Imperial Military (With the Possible exception of the Navy) is much closer integrated that the US Military
Probably something more like the Canadian Military, which has had its services very closely integrated

Since the Imperial Battlespire went boom, I image that Imperial Battlemages receive instruction from the Battlemages who were in the field
at that time. The Training Probably occurs at some remote Fortress, because goodness knows that I didn't see lots of Cadets at the Arcane University

As for non-Imperial Battlemages... Anyone who can swing a sword and cast an offensive spell at the same time is a BattleMage

There are three different definitions for "Imperial Battlemage", depending on what meaning you give to the terms:

1. An Imperial (race) who is a Battlemage (class).
2. A member of the Shadow Legion, recruited by the Imperial Legion from the Mages Guild. May be of any race and may not necessarily be a battlemage as far as his class is concerned.
3. The title of the Tamrielic Grand Vizier/Prime Minister equivalent. Currently the title is held by Ocato, who however somehow resigned to become Chancellor instead. Since the Imperial Battlemage was the Emperor's adviser and there is no emperor anymore, it makes sense, I guess.

Of course, it is possible that the Imperial Battlemage could be an Imperial Battlemage who is an Imperial Battlemage, but that is not necessary.

In morrowind they say something like that. Just missing the Alchemy and Conjuration. :goodjob:

I have always considered that there is 1 "position" of an Imperial Battlemage (Jaggar Tharn style) and a generic Battlemage.

We see Battlemages being applied by the Mages Guild in their questline, guys/girls with some armor, weapons and minor magic ability. Considering Battlespire, I guess these are the same actually. The Mages Guild has under it's wing, with the blessings of the Emperor/Empire/High Council of course, a special offshot of warrior-style mages who are trained for "special situations".

That's how I always thought about it.

It's all explained in Battlespire and Redguard. They're recruited among members of the Mages Guild, and they have to pass a test in the Battlespire. If they do pass it, they're accepted in the Shadow Legion. The hero of Battlespire thought at first he was passing this test, and didn't expect it to be so hard...

Gotcha..was there any real mention of the criteria the Shadow Legion looks for? (I'm assuming this is some elite branch of the Legion like Navy Seals)

I would assume it would be a higher than normal physical stamina and weapon adeptness for the mages as well as a focus on the schools of battle magic (probably including Destruction, Alteration, Conjuration and others).