Elephants are a type of heavy cavalry unit available to the Sassanid Empire in Rome: Total War: Barbarian Invasion.
Description[]
Some three meters tall at the shoulder, these animals are trained only to a limited degree. They cannot be relied upon to always do what they are told, and are known to run wild in battle, crushing friends and foe alike. For this reason, each elephant driver is given a spike (to drive in to the base of the elephant's skull) and a mallet, so that he can kill the mount if necessary.
Assuming that the elephants don't run amok, they are a valuable addition to the shock element of any army. They can also be used to batter down gates and wooden defences too.
Tactics[]
Elephants are a rarity in the expansion due to their loss of prominence over the centuries. Where war elephants were commonplace thanks to powers like Carthage, the usage of elephants has been diminished to India and the Middle East. However, that doesn't prevent the Sassanids from employing them as support and fear tactic units. There's little that can compare to Elephants as they're both good as shock cavalry with a fantastic charge but also as missile cavalry since two archers are mounted in the turret on their back.
They're somewhat a sort of 'loose cannon' unit for the Sassanids, as they bring powerful bonuses but can act unpredictably. When assaulting a walled city, the elephants can replace a battering ram for taking down the gates of a stone walled settlement where the flaming arrows may otherwise burn the ram before it can reach the gate. Likewise, for taking a wooden walled settlement, instead of waiting a turn or two to build siege equipment, an army with elephants can assault immediately and just use the elephants as a ram to break down the walls. Elephants make good shock cavalry thanks to the bonus they get to morale damage, making them good for dealing the final blow to an enemy army when attacked from the rear, as well as making decent, albeit less mobile, archer cavalry because of the bowmen on their backs.
Elephants are a likely late game unit thanks to their building and population requirements as well as their high cost to train. There's far better regular cavalry units that are available earlier with better melee statistics that will pad out the main fighting force of a Sassanid army, though Elephants do have their place. Again, thanks to their morale damage bonus and the archers on their backs, Elephants are a good shock tool and ranged support unit, not to mention they can hold their own against weaker cavalry units such as the Eastern Roman Empire Equites Auxilia and Dromedarii, though thanks to the weak melee stat of the Elephants, fighting melee is not advised. Elephants are best used on the flanks supported by a superior cavalry unit such as Cataphracts or Clibinarii, where the cavalry can drive off any attempted push on the elephants before they can outflank and charge into the rear lines of the enemy infantry. The major thing to remember with Elephants is that fire scares them and can easily spook them, causing them to run amok. Keep them well away from enemy archers as their fire arrows can cause the Elephants to run riot, likely into your own units. Keep them away from your main army as a precaution at all times.