Poland would be jealous: rhinoceros cavalry

Rhinoceros are formidable beasts. Cavalry has been a fundamental element of most military during a long time. Just like nunchaku and lightsabres, adding a formidable element to a proven idea will often result in something as awesome as it is ridiculous. So, as with bear-riding Norsemen or tiger-riding Asians, you would expect it in a comic-book setting: replace boring, practical horses with the most terrifying local animal*. Generally, comic books don't care if something is ridiculous, as long as it looks awesome enough.

* Hippopotames may not be as terrifying-looking as rhinoceros, but they are potentially even more dangerous. Leaving aside that they can attack and capsize boats, they are much faster and more manoeuvrable than they look. But hey, who wants to see goofy-looking hippopotamus cavalry?

This can be a problem when adapting a comic book to film, where the filmmakers have to walk a fine line between respecting the source material, delivering on the promise of awesomness made to fans of the comic, and try to not look too stupid while doing so. Rhinoceros cavalry is what happens when the second point wins out. Of course, for some viewers, especially those favoring hard-SF or otherwise believable fiction, this can be somewhat distracting.

At least it does look good, in its own "brain turned off" kind of way (source)

At first glance, when one thinks about it, rhinoceros would make formidable mounts, cattle and beasts of burden indeed. They are herbivorous, which you want in this case. Carnivores are a royal pain to feed, logistically. Most domesticated animals are herbivorous for a reason, the two notable exceptions, cats and dogs, side-stepping the issue: cats mostly feed themselves, and dogs are small enough to live on animal parts humans don't eat. Their bone and muscle structure seem well enough adapted for pulling or carrying heavy charges. Cows, for example, cannot carry a rider for an extended period of time. Nor could a giant wolf of tiger, alas.

They also have immense physical strength, run at 50 km/h, and can exceed one metric ton. In addition, they will naturally charge and hurt humans in front of them, and their big horn make for a vicious natural ram. Compare this to horses that have to be carefully trained to charge or kick humans, and will spontaneously avoid stepping on them, even humans with an uniform of the wrong color.

Then, why has no ancient culture domesticated rhinoceros to fill the roles of warhorses and cows? Because they have immense physical strength, run at 50 km/h, and can exceed one metric ton. In addition, they will naturally charge and hurt humans in front of them, and their big horn make for a vicious natural ram. Good luck capturing a breeding pair before the Industrial Revolution. And things only get worse from that point on, especially with access to no other domesticated animal. Africa has been one of the most competition-heavy natural environment for large animals, and those who survived are all tough bastards. (Human beings themselves evolved there.)

The terrible character of the rhinoceros not only makes it difficult to capture, it also makes it difficult to hold, as it will charge at barriers and attempt to trample humans on the other side. Including humans behind cover. Or possibly in buildings. Did I mention the pointy built-in ram on their head? In addition, rhinoceros have a terrible character among themselves, so humans could not even use their existing social structure, like we naturally do with horses or dogs. This is basically why horses could be domesticated and not the physically similar zebras. And it is even worse with rhinoceros than zebras, as they are also solitary territorial animals.

It may be possible to alleviate the terrible character problem through domestication, that is the long-term processus of selective breeding that will develop new breeds more adapted to taming and human use - like was done with boars to create pigs. We would probably see new rhinoceros breeds selected for military use, for draft and carriage, for meat, or even possibly for milk. (It may not be possible to have a long-distance runner breed, though this is difficult to tell in advance). After all, there is one known case of a rhinoceros letting a human ride it, so it is at least possible to work with them.

Not as good-looking as horse saddle position, but I would trust the professional.

However, there is a serious problem (or rather, one more serious problem) to domesticating rhinoceros: their reproduction rate. Gestation time is about 16 months, for a litter of one calf that will stay with its mother (preventing new gestations) for two or four years, for male or female respectively. And males will need three more years before starting to mate. All this means that very few new rhinoceros are born each year, and generation are quite long. This makes selective breeding a very slow process, one that will take significantly more than the working years of a human to see progress.

You may point out that elephants share this problem with rhinoceros, but Asian elephants are nice enough to be tameable as they are, even if they have not exactly been domesticated. Do note that African elephants have not been tamed the same way, and that Hannibal's famous elephants were the smaller, now extinct North-African elephants (expect possibly his personal one, that may have been an Asian elephant). African elephants have neither been tamed nor domesticated for the same reasons as rhinoceros, but worse.

So, what would our hypothetical pre-industrial African society need to domesticate rhinoceros? They would need some way to build fences that can stop angry full-speed rhinoceros. They would need weapons that can subdue said angry rhinoceros in the wild, and some way to move it to the fence, or force it to walk to it while stopping it from charging and trampling everything around it. At this point, someone with superhuman strength would help, and some personal protection that can make its wearer survive the enormous kinetic energy of a rhino charge would be mandatory. They would also have to need it enough to justify the hassle, instead of simply having more people work to raise food or as soldiers. And finally, they would need an extremely stable society, so it can plan for very long term and spare the resources for a plan that may take centuries before bearing fruit. Frankly, they would need heavenly assistance.

Oh, right.