Great Battle Sarcophagi

The Ludovisi Battle Sarcophagus depicts a battle between Roman soldiers and barbarian enemies, possibly Goths, and dates from the middle of the third century (250-260 CE). It's remarkable that such  a finely detailed work was produced in the chaotic period. The Roman world was then beset by inflation, plague and civil wars as well as invasions.
The figure in the upper center, presumably the deceased, has sometimes been identified as Hostilianus, the younger son of the emperor Decius. The emperor and his older son Herennius perished in the defeat at Abrittus in 251 CE. Hostilianus died of the plague not in battle. The Romans did, however, win key victories against the Quadi and Carpi in 246-47, and the work may pertain to those events.
It's hard to know if the sarcophagus accurately depicts third century armor and equipment. One soldier at far right wears mail, which was in widespread use at the time. Most soldiers no longer wore the lorica segmentata. Some of the other armor and helmets may be an artistic convention.
Other great sarcophagi are older. A famous one dates from the time of Marcus Aurelius. Second century soldiers wore the lorica segmentata and had rings atop their helmets. Both were largely abandoned in the third century.