I am no Byzantine expert so would appreciate some assistance. My understanding is that they evolved from being dual armed with lance and bow to mixed units of lancers and archers to finally becoming just lance armed. Is this correct and if so when did the changes take place? I am interested in general, but particularly want to understand their arms when fighting the Lombards and Normans in the 11th Century.
I won't claim to be an expert either, but here is my take on it mainly from the manuals.
From Prokopios in the C6th the cavalry appear to be primarily armoured horse archers of whom some also carried a spear. They were certainly also happy to charge and fight hand to hand as well as shoot, but I'm not sure I'd call them "lancers" at this stage.
The Strategikon of the late C6th/early C7th seems to want the cavalry to be double armed but does appear to accept that in reality some will be "lancers" and others "archers" in the formation. Tactics certainly appear to be a "lance charge" being shot in by the archers in the formation. However, (some of) the archers can also be detached to operate more on their own ahead of the "lancer" formation.
The Taktika of Leon (early C10th) basically repeats the Strategikon. However, some historians such as John Haldon think that archery declined in the "Thematic" period.
The Sylloge Tacticorum which is (probably) slightly later than the Taktika has the "line" cavalry in shallower formations than previously with 3 ranks of lancers and 2 of archers. Again the tactic is a lancer charge shot in by the integral archers. This work also introduces the katafraktoi who are similar but in heavier armour and use a "wedge" formation.
The Praecepta of Nikephoros Phokas and the update of that by Nikephoros Ouranos (later C10th and early C11th) are very similar to the Sylloge but the katafraktoi weapons change a bit.
Forgot to mention in the later manuals there are also dedicated small bodies of cavalry, some mainly horse archers, who operate ahead of and on the flanks of the main body.
In terms of the period you are interested in Eric McGeer's "Sowing the Dragon's Teeth: Byzantine Warfare in the Tenth Century" covers the manuals.
John Haldon's book Warfare, State and Society in the Byzantine World, 565–1204, London: UCL Press, 1999 is probably the best study I've read on the Byzantine army, and he goes into detail contrasting performance with the tactical manuals. He contrasts the variety in expectation and performance between the eastern and western themes in 8-9th centuries, the Golden Age of reforms and performance that came after and problems that eventuated after the 3 great Emperors.
What I got out of this for the Thematic Period of the 8-9th centuries was that all was not as clear cut and uniform as the army lists would have us believe! Quality of mounted archery and equipment was variable from Theme to Theme, infantry was below par and everyone was seldom singing from the same hymn book (reference the two periods of Iconoclasm that seriously distracted the central Empire when enemies were pressing from all sides).
I was so inspired I built the army but my performance with it was so appalling that I turned to iconoclasm, sold it and erased it from my memory.
While trying not to hijack the thread....What's the current view in whether Byzantine cavalry ever rode partially armoured / 1/2 armoured horses?
(I have a bunch of them, 1980's Minifigs, which I trot out now and then....just wondering if at any stage they might actually be 'accurate').
Mentioned for front ranks in the Strategikon and Taktika of Leon. The later manuals don't mention it, only the katafraktoi have horse armour in those.
That's good to hear. I've just finished painting a dozen with half-armoured horses. :o
There appears to be no pictorial or archaeological evidence whatever for Byzantine (or Avar) use of half-armoured horses, but shah Khusrau II had himself depicted riding a half-armoured horse at Taq-e Bostan.
The lack of archaeological evidence isn't particularly surprising - only metal horse armour is likely to survive at all, and what's likely to survive is individual lamellae that you can't readily tell if they were intended as armour for a man or a horse, let alone for half a horse or a whole one - but the lack of pictorial evidence is odder, as is the lack of mention in narrative sources.
The best guess is probably that it existed, but was far from universal even among officers and front-rankers.
This book chapter available online may be of some interest: Equestrian Military Equipment of the Eastern Roman Armies in the Sixth and Seventh Centuries (https://trivent-publishing.eu/img/cms/8-%20Mattia%20Caprioli.pdf)
Khusrau's equipment for man and horse is pretty much the same as the Strategikon describes for a fully equipped front ranker 8)
Although he was on the other side. Either he sued the Strategikon for plagarism or he was saying "look what I got, and you don't!"
We're in that conflict where we have the theory but no hard evidence (first-hand accounts, pictorial, tombs etc) of the practice. So close! However, the theory is at least informative of what they wanted to field so there is something to work from.