Complex sentence: Galba succeeded so far as to put the enemy to flight; but as with his exhausted and undisciplined army, he was incautious in their pursuit, the Lusitanians turned around, and a fierce contest ensued, in which 7000 Romans fell.
Split into simpler sentences: Galba succeeded so far as to put the enemy to flight. But as with his exhausted and undisciplined army, he was incautious in their pursuit, the Lusitanians turned around, and a fierce contest ensued in which 7000 Romans fell.