What would T-Rex cavalry be used for?

Question

In a world where prehistoric animals from the late cretaceous and cenozoic period exist such as arctodus simus, triceratops horridus, etc. is there a use for riding a t-rex into battle? The people already make use of triceratops as heavy cavalry for obvious reasons, so that niche is filled. I was thinking that since there is some evidence for t-rex being a social animal it should probably be trainable, especially since food is not a problem due to being able to farm extremely large animals like hadrosaurs. The world doesnt have magic, but supernatural animals such as dragons and extremely large variants of existing animals exist, although they are quite rare.

[edit] I was thinking that they would make good special forces since the T-rex is better at stealth with its foot pads and naturally knows how to ambush prey, also scaring the enemy's animals since it is their natural predator. also, i never said it was an era before refrigeration or some kind of food preservation. It's perfectly plausible to preserve meat with salt or iceboxes, or in the worst case scenario just bring a living animal with you and kill it when the t-rex looks hungry. I agree that t-rex riding is not actually necessary since it would be rather impractical.

Answer 1

They will be most valued by scouts and sentries

The T-Rex is believed to have had the best sense of smell out of any dinosaur, and possibly even the best out of any animal that has ever lived. The olfactory regions of a T-Rex brain and the olfactory bulbs were so over developed compared to other dinosaurs, dogs, etc. that paleontologists believe that the T-Rex could smell prey from many miles away.

This impressive sense of smell means that T-Rexes could be used to track down enemy armies or alert your forces of an army that is trying to close in on you.

In addition to being a peerless tracking animal, They are also individually fierce animals. Unlike cavalry which rely on power en masse, scouts typically operate alone to mitigate risk. Since scouts will tend to be 1 rider, 1 mount, having something as fast and strong as a t-rex that other dinosaurs will instinctively fear means that if he is caught, his ability fight back or get away from a light patrol is much better than if he were on a less apex predator mount.

Finally is the food budget concern. No matter how much food you have access to, herbivores are always going to be cheaper than carnivores meaning that it will be very expensive to field more than a few of them. By being used as scouting mounts instead of rank-and-file cavalry, you do not need a whole lot of them to meet demand or to justify their cost. For example, a typical medieval or ancient army would have had no more than 100 scout horsemen, could easily have thousands of cavalry.

If making them a front-line "cavalry" unit is important for plot reasons

A T-rex can probably beat a triceratops anywhere he has the space to out maneuver it or where there is not enough space for the triceratops to muster a charge, but against a mass of them charging shoulder to shoulder, they don't have the anatomical features to stop a fast moving wall of spikes or to bypass their bony frills when forced to fight them face to face. They can maybe pick off a few from the flanks, but can't stop a charge. Given the added cost of fielding a t-rex, they would have to be an elite unit which seems counterintuitive for something that will do worse in a main battle line than your cheaper, better triceratopses.

That said, there is historical precedent for making elite units out of "inferior" troops. Alexander the Great built the core of his phalanxes out of Phalangites (aka: pikemen). In a head to head fight, their longer spears made them unbeatable, but it also forced them to fight in tight, ridge formations. This left their flanks very vulnerable; so, Alexander used Hypaspists who were his strongest, most well trained infantry and gave them shorter spears and lighter armor so they could fight in more flexible, open formations, and could adapt better to difficult terrain.

Like the t-rex, a Hypaspist demanded a higher salary and would be unable to beat a Phalangite in a head-to-head fight, but they were a necessary measure to cover the Phalangites vulnerabilities. So, you could build your cavalry formations following this same logic. You make the core out of a large number of triceratops which fight very well en-masse but require a tight ridged formation and put smaller units of loosely packed t-rexes on the flanks and in reserves where they can guard the triceratopses from being out maneuvered and better adapt to the unexpected conditions of the battlefield.

Lastly, if the triceratops get stopped and forced into a deadlock, scenario with another triceratops unit, the t-rexes could wrap around to flank enemy triceratopses who are now too tightly packed to charge or maneuver to defend themselves.

Answer 2

Not at all, or same as elephants

To imagine a T-Rex cavalry we can start with an analog. Elephants. The African bush elephant bull is 3.2–4 m (10–13 ft) with a weight of 4,700–6,048 kg (10,362–13,334 lb). The T-Rex is larger, with an estimated 4,6-6 m (15-19,5ft) and 5,000-7,000 kilograms (11,000 to 15,500). So there is some overlap, though in general the t-rex is bigger. At these sizes it might surprise you that it isn't that much bigger. Especially if the T-Rex is walking, where it'll lower it's body. You can imagine the average T-Rex as the largest elephants to roam the planet. Elephants were used in warfare, so it starts off great.

It starts looking as a great choice. Elephants were used for charging enemy ranks, scattering troops and instilling fear. The T-Rex can do all of the above. It has a big bite to boot, which can be more effective in instilling fear than trampling. We need to talk about the downsides however.

A T-Rex can raise and lower it's body. This makes it more difficult to create appropriate riding gear. It'll need to account for a huge shift in angle of the back. You can get around it with more training, ordering the dinosaur around like an attack dog. Regardless of solutions in riding gear or other, it becomes more complex.

Charging the enemy also can become difficult. An elephant has four legs and is a stable platform. If one is injured in a fight, like trampling a soldier and some part of the armour pierces the flesh, it can still get away. A T-Rex has only two legs for locomotion. An injury could immediately take it out of the fight, as well as be a death sentence.

This leads great to the next point. Predators are cowards. They generally only attack if there is a high likelihood of not getting injured. An injured elephant can limp to a tree and eat. Any predator will be unable to hunt. This makes a T-Rex a poor choice as cavalry. Predators in general are genetically programmed to avoid injury to a much higher extreme than a herbivore. Where being sick or injured can be dangerous for any mammal, the predators will have a much harder time. Social groups like lions or humans can still engage in risky behaviour, though you'll still see that they try to have overwhelming odds to win the fight. If it needs to charge or bite some infantry bristling with spears, would they really do it? It is likely hard to train that into the animals and the return could be relatively slim.

It is also difficult to give armour. It's abdomen and head are likely targets. If you armour those, you'll put weights on one side of a creature balancing on two feat. In other words, it's not balanced any more. An elephant in contrast can be armoured from one side, allowing much higher survivability.

The final nail in the coffin isn't even battle itself. It is simple logistics. A T-Rex requires a load of premium food. Meat is more difficult to get than leaves or grass and can be eaten by your soldiers. You'll need a special supply chain just to keep them fed. As they say, logistics win battles and not armies. Severely complicating your logistics, not to mention increasing cost by a huge margin, is never a winning strategy. Simply put, they lose wars by just existing in your army.

Conclusion

You could conceivably have a niche for a T-Rex in a battle. It is big, powerful and scary. However, their role is done better by a humble elephant. They are less powerful and scary. They still are better at trampling, training and logistics, can be better armoured, are able to forage off the land, require less expensive gear to ride and are in general less expensive overall to maintain in and outside of war. A T-Rex as cavalry is a great rule of cool. It is bad regardless.

Answer 3

Frame Challenge - Rule of Cool is in effect

Sometimes on this site, Good Worldbuilding is providing a detailed, well-reasoned answer to a particular problem.

And sometimes good worldbuilding is to tell the querant that the less time and effort they use to justify an idea, the better - because it allows the reader to fill the blank space with their imagination

This, I feel, is one scenario where it is definitely the latter.

T-Rex Cavalry sounds cool.

I say this as someone notorious for commenting on Military questions with wild-abandon (they are one of my favorite WB questions to answer).

Trying to justify T-Rex cavalry as having some niche special function or purpose will take away from the reason you want T-Rex Cavalry: Because it is Cool!

You say you are in a prehistoric setting and you tell me you have Triceratops heavy cavalry and T-Rex Cavalry - Fuck it, I am invested - we ball.

And so my answer is that this is a classic scenario where I would recommend that less is more - do not try to give them a reason for existing or a special purpose - just that you have T-Rex Cavalry.

Answer 4

Kind-of frame challenge

Why would you want to use T-Rex cavalry? The triceratops you've already got are bigger, more stable, and faster. T-Rex might have more stamina (no idea), but if you can train both of these types you can surely train some lighter dinosaurs that would outperform both for scouting and light cavalry. So apart from rule of cool, what's the point of using T-Rex cavalry? I assume it's mostly to do with its fighting abilities (all those teeth). But in that case, a human rider is perhaps just a hindrance. So consider getting rid of the rider and training them as riderless combat animals, similar to attack dogs.

As one ancient playwright (best known for his habit of waving weapons around outside his cave) once wrote, "Cry Havoc! and let slip the T-Rexes of war!"

Answer 5

T-Rex is the most trainable and domesticatable dinosaur (in your setting) (because you say so). Sure, Whateversaurus is harder, better, faster, stronger, and a more stable riding platform, but have you tried getting one to sit, stay, fetch, and not eat your daughter?

It's not like we're ever going to have real life data about the train-ability of dinosaurs, so you can just declare reality to be as you want in that regard.

Answer 6

Your biggest problem: Training

So, we have, already, some amazing large predators. Why don't we see them fielded by the ancient world?

Because training them to handle loud noises, injury, etc, etc without either running away or mauling their own side is really, really difficult.

I'd imagine T rex is basically a scaled up bear. Relatively solitary, probably with territory, mean, with scavenger and hunting abilities. Put this on the battlefield, with hundreds of screaming humans chucking spears at it, and this thing is going to take it out on you.

So, how to use them? Well, possibly, they're big enough and mean enough to use in defence. Rather than cavalry, you drop the drawbridge, the enemy runs towards the fortress, and then 20 furious, starving T-Rexes storm out. You could, with difficulty, use them on the battlefield in a similar way - point towards the enemy, make sure you're out of the way. You'd probably constrict vision in some way, so they can see the enemy but not you, and then release them from some sort of harness to charge the enemy.

Answer 7

Anti calvary calvary.

T-rexes would be elite units, they cost a lot to feed, although you can make some of that up by feeding them defeated enemies, human are nice but dead calvary will go a long way during a campiagn to feeding it. The real expense is when you are not at war, you need to generate a lot of food.

What are t-rex good for, they are big powerful predators capable of out maneuvering animals of similar size and overpowering anything smaller. The can deliver extrememly quick lethal force to other cavalry or eally any vunerable unit. So what do you use somthing expensive maneuverable and powerful for, elite anti-cavalry cavalry. Normal anti-cavalry tactics don't work great against dinosaurs, spears don't scale well to big dinosaurs and have a harder time doing major damage. Dinosaur cavalry will be slower but much harder to stop.

What do I mean anti-cavalry cavalry, they are a fast moving unit that can intercept and stop enemey cavalry.

We've never seen anything like this in real life because no comparable animal exists, large warhorses outweigh all terrestrial predators. Also horses are all roughly equally maneuverable. A t-rex is more maneuverably than somthing like a triceratops. Note they don't need ot wipe out the cavalry they just need ot keep them locked down and pick them off if they try to break. Of course if you also have regular/triceratops equivilent cavalry then the two together can easily wipe out enemy cavalry. Keep in mind dinosaur cavalry will not be as fast as horse cavalry with the cempesation that they are a lot harder to stop so the t-rex cavalry becomes even more useful. Stopping the cavalry's movement is essential. I see trex circling or getting behind enemy cavalry with the helpf of their own cavalry, the enemy can't advance they have to try to keep in a defensive formation.

T-rex are pack hunters so they will work well in army tactics, instictively they will try to break up defensive formations. The hardest traingin will be making them more aggresive and less risk adverse. Also teaching them to not stop and eat after a kill.

They would also be good as an elite strike force, send them out to attack artillary or supplies, other slow moving units. They move fast enough and can do a lot of damage in a short time. So they do make rather effective normal cavalry as well. Note smaller cavalry will be a lot faster so they are not scouts and not your fastest units just fast enough.

What are the humans good for

Of course first you want them to steer but if you put a few archers over a t-rex's hips (otherwise you unballance them) you improve their defense and striking power. maybe train them to fire as the t-rex retreats or passes to minimize counter attack. No melee weapon will be useful, you are just too far from anything. Note archers are not doing that much to well trained large dinosaurs, their target is the people.

Answer 8

Status

It is a glorified, and historically accurate, version of the "rule of cool". High-ranking warriors, kings and so on have been historically using weapon systems that are not particularly useful, but demonstrate their high status.

Elephants is a very good example, detailed in the great series by Bret Devereaux (whose blog is a must-read for any aspiring world builder !). This, and following: https://acoup.blog/2019/07/26/collections-war-elephants-part-i-battle-pachyderms/

tl;dr: Elephants were useful as a weapon system, but not particularly overpowered. Elephants are great as part of combined arms, especially against fixed-formation infantry (phalanx) because of their ability to rupture the enemy's formation. On the other hand they were not very useful against any army with a moderate degree of tactical flexibility and/or light projectile troops (Romans !), and fielding them requires a large investment (it takes time to breed elephants). So it is a lot of resources spent to field a weapon system that is good but not great, and that everybody knows how to counter at a fraction of the price - when the Romans got access to elephants (after conquering Carthago) they did not use them, even though they did inherit their region of origin.

However, in some parts of the world (India) elephants were used much latter. Partly because they are easier/cheaper to field there, within their main habitation range; but also, and mostly, because they demonstrate a high status, both physically (you are sitting meters above the peons) and metaphorically (look at this cool king looking so glorious atop his mighty beast). To quote Devereaux's conclusion: "elephants were useful not only as weapons, but as symbols of military might".

So it is the rule of cool - with a good historical reason. A badass warrior king will want to sit on a T-rex, not so much because a T-rex is a great weapon (although it may be an Ok one) but because it makes him look cool and badass....

Answer 9

I think a t-rex would be good for fighting, and since they were likely ambush predators, surprise attacks would be a good use for them. Since they were pretty big, it would prevent people from reaching the rider with melee attacks, though without armor the dinosaur would be pretty susceptible to every sort of attack, especially being such a big target. Generally I think they'd be used mostly for offensive attacks where there's a lot of people/dinosaurs who need to go bye-bye.