Here is an excellent link towards one of my older fantasy.
Happy to see that one is shared by someone

http://home.netspeed.com.au/reguli/fanro1.htm

I specially like that subject

Drake, David & Morris, Janet, ARC Riders: The Fourth Rome. New York, Warner Books, 1996.

A novel in another ‘time patrol’ type series, this one concerns a team of men and women from roughly the same era used by beings from further up-time to prevent people from meddling with the timelines. Unlike in the "Time Scout" series, history can be changed.

Someone from the crumbling Soviet Union of 1992 has gone back to 9 AD to stop the massacre of three Roman legions under Varus by Arminius and his German tribesmen in the Teutoberg Forest which effectively froze Rome’s further eastward expansion. These revisionists want Rome to continue in to Russia and so to change history. Half the ARC team remain in 9 AD Germany to track down the revisionists and see that Varus and his legions meet their fate while the other half goes to Moscow in 1992 to find out how it is that 20th century operatives use such advanced technology.

The story is balanced between the two eras about equally and makes for gripping reading, especially in the Roman segments. The authors create characters to care about like the soldier, Flaccus, and realistically depict legionary life in camp and on the move. There are no real villains here the Roman general might be stupid and corrupt but the German leaders are treacherous and cruel and as usual the poor sods on the ground wear it.

(For another non-fantasy treatment of the same events, there is the historical novel by Gregory Solon, The Three Legions, Constable, 1957, reprinted in Tandem paperback in 1972).

THAT ONE SEEMS ALSO GOOD:
Drake, David, Ranks of Bronze. New York, Baen, 1986.(Originally published in a slightly different form as a short story in 1975.)

What happened to the men who survived Crassus’s disastrous defeat by the Parthians at Carrhae in 53 BC? In this novel Drake postulates they were sold by the Parthians to aliens who use them to fight wars on low-tech planets where advanced weaponry is strictly forbidden. On each planet they fight as usual with javelin, sword, shield and standard Roman siege machinery but aboard the alien vessel they are subject to their masters’ high technology which keeps them from aging - in the body - repairs grievous wounds and even restores the dead provided the central nervous system is not destroyed.

The novel recounts several campaigns on different worlds, not only how they deal with their alien opponents but how they grow and change as the result of their experiences, and how gradually they determine to go home again unaware or uncomprehending of how many centuries must have passed. The alien masters are depicted as coldly efficient, even cruel at times, but not unnecessarily so. They have the attitude of an owner to clever and resourceful pets but gradually the tables start to turn as the Romans realise their power.

This is a very gripping book with vivid scenes of battle but also good characterisation and development.