A while ago, I asked In what war would one modern military vehicle make a difference? I have now come up with a sort-of sequel.

A modern, Challenger II battle tank has been sent back in time to a past war. It was decided in my last question that this tank would indeed have some significant impact on the war. What was not shown is how long the tank would be effective for.

That's what I'm asking now. In this question, I'm looking for comparison of how long my Challenger could last in various historic wars, assuming:

  • No restocking on fuel or parts from the present; the time machine has been destroyed
  • Unlimited knowledge of the tank can be taken back by its crew and shared with anyone else who might need it
  • In-period manufacturing techniques and technology
  • The tank is rendered ineffective when it can no longer move or shoot.

For example, it might last longer in WWII because the factories would be more capable of producing armor for it and it might be able to run off fuel from the time. I doubt it would last so long in a war before vehicles were invented.

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    $\begingroup$ Which war(s) are you asking about? Just ones with British involvement? $\endgroup$ – Samuel Apr 22 '15 at 16:17
  • $\begingroup$ Do you mean the transported tank/crew can't get fuel reserves from the present, or that the tank can't be restocked with fuel at any time? $\endgroup$ – Frostfyre Apr 22 '15 at 16:18
  • $\begingroup$ @Samuel Any historic war. Specifically, a comparison of two (or more) $\endgroup$ – ArtOfCode Apr 22 '15 at 16:28
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    $\begingroup$ @ArtOfCode I just mean if anyone can pick any war then valid answers will range from one day to years. It makes the question rather broad and the answers uncomparable. For instance, the Iraq War ended in 2011 and, as any war would, it fits the definition of historic, but it doesn't make for very interesting answers. $\endgroup$ – Samuel Apr 22 '15 at 16:32
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    $\begingroup$ There is an objectively correct answer for each war. Why not pick three? $\endgroup$ – Samuel Apr 22 '15 at 16:40

11 Answers 11


Probably the biggest factor in determining the transported tank's viability is going to be fuel availability. The Challenger 2 uses a diesel engine, so the tank will only be useable for about 160 miles (250 km) -- off-road operational range -- prior to the invention of diesel fuel in the 1890s.

So we'll take a look at wars between 1900 and 1945, since you mention in comments that you want to know WWII and earlier. The Challenger carries 52 rounds with its main cannon. Since this is state-of-the-art ammunition, it can't be constructed with WWII technology, let alone WWI. While the Challenger's armor is classified, it's safe to say that even a Tiger II would have significant trouble, if not find it impossible, to actively penetrate the tank's armor. Eliminating the tank would have to be done by a specially-equipped team of infantry, specially-designed artillery, or aircraft.

Because tanks didn't see much use prior to WWII, there was no ultimate strategy for combatting tanks from the air. The typical plan was to drop standard bombs on the thinner armor on the roof. There's a pretty good summation of anti-tank tactics and weapons here. Since this is all still WWII technology, it's going to be mostly ineffective against a properly prepared Challenger 2.

In conclusion, a Challenger 2 transported back to the first half of the 1900s will probably defeat itself before it is defeated by the opponent, mostly by running out of fuel or ammunition. If by fuel, you'll get up to 6 hours of lifetime. If by ammunition, up to 52 shots; after which point you'll have to find an inferior alternative or resort to the mounted machine guns.

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    $\begingroup$ the mounted machine gun is a VERY game changing weapon of it's own. If they can simply keep that restocked they would still have a pretty powerful weapon, though I don't know how hard it is to keep it stocked. they could even resort to simply running over infantry. It wouldn't be all that lethal, but it would have a nice terror weapon approach, no one wants to move toward the armored death machine even if it's not all that great at killing you by running you over. $\endgroup$ – dsollen Apr 24 '15 at 12:52
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    $\begingroup$ Could it run on biodiesel? (en.wikipedia.org/wiki/Biodiesel). If so then all you need is one crewman who knows the recipe, and a government capable of producing the necessary quantities of fat and ethanol. That might even be possible in medieval times, and Henry VIII certainly could have arranged it. $\endgroup$ – Paul Johnson Jan 19 '16 at 21:20
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    $\begingroup$ Mark's answer is correct, diesel engines are very forgiving and will run off almost any liquid hydrocarbon... though it might be hell on filters and gaskets. As for the tracks, they can be repaired by the crew. $\endgroup$ – Schwern Apr 25 '16 at 1:06
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    $\begingroup$ Rather than a Challenger 2, an M1 Abrams has a Gas Turbine powerplant. These should be much easier to run on pre-modern fuel refineries. $\endgroup$ – Aron Apr 25 '16 at 2:05
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    $\begingroup$ In warm environments, straight coconut oil can be used in diesel engines with no modifications. If it gets cold, the oil needs to be preheated. $\endgroup$ – Thorne Sep 13 '17 at 1:27


For the most part, fuel is a non-issue. Diesels are generally quite forgiving when it comes to fuel quality, so you can run the tank equally well off of refined diesel or lamp oil. The further back in time you go, the more expensive it is to fuel it, but you can probably go back several thousand years before you lose the ability entirely.


As others have mentioned, the main gun uses highly sophisticated ammunition. If you go back more than a few decades, you lose the ability to make more at any price. However, it also has a chain gun and machine gun, both of which use fairly conventional cartridge-based ammunition. You could mass-produce this clear back to the mid/late-1800s, although with an increased rate of jams from WWI on earlier due to sloppier manufacturing tolerances. If you're willing to pay premium prices, you could get hand-made cartridges clear back to 1820 or so, with the invention of the percussion cap.

Spare parts

This is the tricky part. The Challenger 2 is made using modern high-strength alloys and manufacturing tolerances.

The electronics are probably irreplaceable before the 1980s; the armor before the 1960s; but neither is likely to be damaged except in a combat situation that destroys the tank.

The most likely failure point is the engine, drivetrain, or tracks. If the failure is in a tolerance-critical part, trial-and-error fitting could make a replacement back to the early 1800s with the invention of high-hardness tool steels; before that, no amount of effort will give a good enough fit. If the failure is in a strength-critical part, you could probably make a replacement back to 1900 or so; before that, the lack of high-strength steels means that a replacement part that is strong enough won't fit in the available space, and vice-versa.


Your fuel supply is good for about 250 km before needing to find a local supply, your ammunition will last you one to two battles, and you'll probably suffer an immobilizing drivetrain breakdown around the 10,000 km mark. If you're fighting in a recent enough war, you may be able to solve these problems.

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    $\begingroup$ While you'd lose the superior accuracy, range, power and rate of fire, you could still modify the main gun for black powder ammo - cast slugs, black powder loadout, a tiny channel to drive the fuse. The barrel has more than enough durability for that and while precise shells with percussion caps would be impossible, modifying the main cannon to shoot makeshift ammo should be well possible. $\endgroup$ – SF. Apr 23 '15 at 13:46
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    $\begingroup$ @SF but it would have a very small caliber (= destructive power) by the standard of the era. With modern ammo it would be more than offset by HE rounds and the muzzle velocity, but if you go back to black powder, you get little more than a (very heavily armored) falconet. $\endgroup$ – SJuan76 May 28 '15 at 13:30
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    $\begingroup$ @SJuan76: The primary challenge in making rifles is the rifled barrel and the material engineering behind its durability. Cast slugs would still outperform any contemporary guns in matters of combined range+accuracy, and possibly quite a bit more piercing power than round cannon balls. Plus it's better to have a very heavily armored falconet than not to have it. $\endgroup$ – SF. May 28 '15 at 13:48
  • $\begingroup$ @SF Rifled breech-loading cannon have been available since at least the mid 19th century, so I don't think the main gun would be all that impressive without modern ammo. $\endgroup$ – Deolater May 28 '15 at 17:48
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    $\begingroup$ @Deolater: In IIWW (and even IWW) it would be possible to manufacture ammo pretty much matching the specs of the tank's standard ammo, and it would make little difference, being simply one of better tanks in the field but still easily incapacitated by an anti-tank mine, or most anti-tank counter-measures capable of stopping the heaviest tanks of the time. The superiority of modern tanks is their mobility vs the "tracked bunkers" of the time, plus defenses against measures rarely available then anyway (HEAT ammo, missiles). But in Napoleon's army it would be quite fearsome. $\endgroup$ – SF. May 29 '15 at 9:00

I won't address the parts/fuel/ammo part of the question as others have already done so.

How long a single armored vehicle would last would depend largely on the way you operated it, regardless of the war you time-traveled back to. Is it basically stationary, guarding a specific area and only moving as necessary to get line-of-sight on incoming enemies, or is it on the move every day to keep up with an advancing army?

In the first case, sitting basically stationary, it could last quite awhile. You could use spotters to sight incoming enemies (and shoot minor threats) and only fire up the vehicle as needed, to move to a better firing position or charge the batteries, for example. In a single position like that, especially if the crew knew ahead of time to prepare for such a role and packed accordingly, the vehicle would probably remain operational until it ran out of ammo or the position was overrun and it was set on fire (or it was pounded flat with artillery or mortars, depending on the time period).

How long the ammo would last is, of course, an entirely different question. Hours? Months? It's impossible to say without more information.

If the vehicle was on the move every day I doubt it would last two weeks, even making short daily movements with unlimited fuel. One of two things would happen: it would become immobile due to breakage; or it would become stuck with no possibility of recovery without other tracked vehicles to pull it free. Tracked vehicles are impressive off-road, but when they get stuck or break down it takes major effort to recover them. Something as simple as a thrown track in a bad spot with no other tracked vehicles to help could mobility-kill the vehicle.

Luck and the crew's competency both play large parts, but I honestly would not be surprised if a single tank or armored fighting vehicle mobility-killed itself on day one even with a skilled crew.

Source - 4 years as a mechanized infantryman in the 1st Cavalry Division. I worked with M2A2 Bradleys and M1114 HMMWVs for the most part but my company had an M1 Abrams platoon attached to it as well.

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    $\begingroup$ Keep in mind that Stonehenge was built without tracked vehicles, and those rocks are pretty darn heavy. Retrieving a tank that got stuck somewhere would become significantly more expensive as the technology became more primitive, but the tank would also become more valuable, and therefore worth retrieving. A thousand men with picks, shovels, and determination could probably get it out of almost anywhere given enough time. The only question is whether it would be worth it or not. $\endgroup$ – Perkins Oct 22 '15 at 0:18
  • $\begingroup$ A large team of draft horses would also be useful. Trained, bred for the job, draft horses were more common in the periods being discussed here than they are now. See: Two horses pulling 18,000 lbs. $\endgroup$ – Patricia Shanahan Jan 12 at 23:24

With the support of a nation, the tank could be maintained as a devastating combat vehicle from roughly the mid 19th century onward. Far more important than it's ability to kill things, the Challenger 2 could turn battles and whole campaigns as the ultimate command vehicle.


As others have pointed out, fuel is not a problem. Diesel engines will run on almost any liquid hydrocarbon, though it might be hell on the filters, hoses, and gaskets. These could be replaced with natural equivalents (rubber, cotton, wool) but they would have to be serviced more frequently.

Main Gun

The main gun will be fun for a battle or two until you fire all 49 rounds of the standard load. It's possible shells could be manufactured for it, modern brass cartridges with smokeless powder begin appearing in the 1860s, but the materials and tooling to create them were known far earlier. Even black powder would work, but it would require extensive cleaning else it would foul the barrel. The lower pressure of contemporary manufacture shells would be a boon as it would serve to preserve the rifling.

It's possible to replace the main gun entirely with a breech loading cannon of equivalent weight starting with the Armstrong gun in 1855. The existing L30 gun weighs 1800 kg which could handle any number of mid 19th century heavy naval or field guns. The ability to move a heavy gun around the battlefield with impunity would be devastating.

Machine Guns

The machine guns are arguably of greater utility on a pre-WWII battlefield to mow down infantry. They use 7.62x51mm NATO introduced in the 1950s. With examples to work from it would not be difficult to manufacture more. Depending on the era, the ballistics and charge might not be quite right. The biggest problem would be ensuring the ammunition is consistent enough to cycle to mechanism.

The commander's L37A2 is a variant of the FN MAG, a gas operated machine gun. This is fortunate as the gas system can be adjusted for the differing power of the locally manufactured ammunition.

The L94A1 chain gun, also using 7.62x51mm NATO, is even better for local ammunition if it can be kept powered. The external drive means it does not rely on the ammunition to cycle the gun. Any underpowered rounds will not result in a stoppage, the gun will fire as long as there is power and ammunition. As long as the batteries hold out, and the tank's alternator works, the chain gun will fire whatever ammunition fits in the gun.

Like the main gun, the machine guns could be replaced. The commander's roof mounted gun could be replaced with a Gatling gun. The coaxial gun, with only a small hole to fire through would have to wait for a single barrel Maxim gun.

Drive train

Here's the real maintenance problem, the drive train: the engine, suspension, and transmission. Tanks are limited by their drive trains. Since everyone wants to shove more weight onto a tank, more armor, more equipment, bigger gun... tank drive trains are notoriously overworked. They have to transmit power to move 60 tons at 60km/h. Worse, they have to accelerate all that mass. This puts tremendous strain on the drive train.

Modern tank drive trains are cutting edge technology. They require careful and lavish maintenance. And they are irreplaceable. Even if you know how to fashion the parts, it's unlikely the metallurgy is available to handle the stresses and heat of a modern tank drive train, as well as the milling technology to meet the required tolerances. Locally fashioned parts might work, but at reduced performance and increased maintenance. Once something really vital breaks you have an immobile pillbox. A Challenger 2 maintenance schedule would shed more light on this, but I can't find one.

Careful driving of the tank, keeping acceleration and torque low, avoiding high speeds, and moving it around on flatbeds (rail cars being the only thing able to carry 60 tons) as much as possible, would extend life.


Here's where it gets really interesting.

The Challenger's rangerfinder, optics, and night vision would allow it to scout the enemy from thousands of meters away, through smoke, and at night. Even if the electronics failed, the backup optical sights are still of extremely high quality. Once those failed, replacing it with a good telescope would be valuable.


It cannot be overstated how bulky and awful military radios were up until even the 1980s. The Challenger 2 uses the Bowman system. Having a powerful, reliable, multi-frequency radio in a mobile armored box would be devastating. Even once the original radio failed it would have the space and power to carry a bulky Marconi radio. So long as there is copper wire, such a basic radio could be manufactured.

The Ultimate Command Vehicle

This is the most overlooked military advantage. Battles are won and lost on intel and communication. In an era where communications are still done with bugles and flags and runners, a mid-19th century commander who can be everywhere and know everything would rule the battlefield. Whomever has the Challenger 2 has the mobility, armor, and optics to scout the enemy with impunity, and communicate that information.

Imagine an army who has equipped their major units with basic, if bulky, radios. Their commander is in the Challenger 2 racing back and forth across the battlefield with impunity, getting first-hand information, disseminating it to their troops, and issuing orders in real time. They can scout any position, even though smoke, haze, fog, rain, and night. They can rapidly react to any change in the situation ordering their troops to react appropriately, concentrating where needed.

Even with no weapons, so long as the drive-train works the Challenger 2 can win mid-19th century battles.

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    $\begingroup$ A single radio by itself is useless. Is the Challenger's radio capable of working in the clear on AM or FM, or does it use only modulation techniques (encryption, frequency hopping) that can't be duplicated using simple analog circuits? $\endgroup$ – Mark Apr 25 '16 at 7:37
  • $\begingroup$ @Mark I can't find information about that, but as they're basically little computers I think it's safe to assume it has a mode which can transmit in the clear. It's moot because, as I pointed out in the answer, radios and generators aren't hard to build, if you know how, even in the mid 19th century, and there's plenty of power and space in a Challenger 2 to fit one. $\endgroup$ – Schwern Apr 25 '16 at 17:09

In one scenario, potentially not long at all.

In contrast to the other answers, a Challenger II battle tank in World War II (or I) would catch the attention of the opposition very quickly. It's location and vector could be very well known. Quickly a trap could be constructed whereby the tank falls into a deep trou de loup and is rendered useless until the crew must expose themselves to firepower to try to dig themselves out.


Other have pointed out what the weaknesses of this one tank are. But the big game changer here, especially when talking about the two world wars, is not the tank, but the "unlimited knowledge" about the tank. Although it can be assumed to be impossible to re-create the challenger2 or a leopard2, or even an abrams, all that knowledge should still help the contemporary industry to build much better tanks.

So, while the individual tank will be rendered useless sooner or later, the side the crew chooses still has an enormous advantage.


The easiest way to disable such tank would be, obviously, by attacking its weakest element: the crew.

Crew members can be tricked; the enemy lord may submit and offer a celebration dinner to his new Masters. Too late, the crew members discover that the cook has developed a taste for adding arsenic to the food, or that the guards have confused the crew with the meal, slicing them in little pieces.

Even without treachery, a patient enemy may wait until the members get out of the tank (to eat, bathe, and other necessities) and take them one of one.

A more drastic option is the use of explosives. I remember reading about Palestinians settings mines with lots of conventional explosives against Israel heavily armored Merkava tanks... when they succeeded, the tank was not affected, but the crew was killed due to the shock.

Of course, the more basic the civilization, the more complicated the trap is/the more time they need to setup it/the more risk of it backfiring, but they are far from defenseless.

Another alternative would be mining a gallery and letting it collapse under the tank; of course it needs being able to predict where the tank will pass through (or steer the crew towards that point).

Finally, a point that nobody has talked is how far the tank could move due to terrain. After all, I doubt that any bridge built before the 1900s (even if brand new) would have enough width and structural integrity to support the pass of a tank.

If you find a barge big and strong enough to ferry the tank, this makes for an ideal point of ambush; a single man with an axe or a torch may sink the barge and the tank with it.

So, yes, I think there are ways to defeat that tank. Many of them will involve lots of patience and effort, and a high risk of the attack being discovered (causing lots of casualties in the retaliation), but definitely there are ways to finish the tank.


Multi fuel diesel engines can burn a fairly wide range of fuels, so if "unlimited knowledge" also means the ability to tune the engine, it may be possible to go farther into the past by burning vegetable or whale oil. With unlimited knowledge the crew might also be able to reproduce the reactions needed to create biodiesel as well.

Of course this creates a cascade effect, biodiesel, for example, tends to clean engines of deposits and the resulting mess gums up the filters. Recreating the specialized materials for engine oil and fuel filters could become challenging the farther you go into the past.

The real sticking point isn't so much the knowledge, but what sort of industrial base you will have access to. Going farther back than the 1980's you will actually have difficulty finding tooling that can repair or replace items on the tank, and going past the 1960's you are essentially looking for the tools to make the tools. As noted, much of the other equipment like the computers and ammunition will be essentially impossible to reproduce.

A bit of a historical BTW, the Germans had prepared a tank busting airplane in the form of the AEG G.IVk (k for kanone) for the expected battles of 1919, and British "Contact Patrol" fighters were equally capable of dealing with hard ground targets (although the Germans did not actually have much in the way of tanks). These, of course are capable of dealing with period tanks, but a well placed burst of 20mm cannon fire across the upper surface of a modern tank could damage the optics and make the sights ineffective.


Tanks are designed with a limited amount of different screws, the purpose of that is in case of a breakdown one can take screws from a less important part of the tank and make a more important part working. This is really effective to make the tank move on even when it is almost totally destroyed.

Diesel tanks are able to run on different types of oil based fuels. Many trucks are running on bio-diesel and i think that MC. Donald's transport trucks runs of filtered deep-frying oil. Though it is sparse, oil is available for a long while back mostly from whales, used to fuel lamps - it could be possible to filter that oil to make it run though it would be terrible expensive none the less possible.

In the defense category, the tank is built to hold against an estimated of 50-100 times as powerful shot as a 12 pounder cannon, meaning The Monitors cannon (30lbs) would barely leave a dent, the most dangerous situation that would leave the tank in was if the belts was broken and the tank was siege'd waiting for the crew to get hungry or ambushed trying to get out to repair the track - though the crew might be a bit shaken and get some bruises from the shaking upon impact.

So the most "dangerous" variable in this case is ammo and money. If you got plenty of both, the tank can run for a good while.


Choosing your war wisely is a useful approach. Even without refueling or rearming, any modern tank plopped down in the middle of England in the eleventh century, before the wide availability of gunpowder, 50 rounds from a cannon and a few hundred rounds from a chain gun would win the whole war.

When the US dropped atomic bombs on the Japanese at the end of WWII, they surrendered not because they were beaten in battle, but because the US demonstrated (with repetition) that they had the technology to wipe them off the face of the planet. As horrible as that situation was, it worked.

Park a tank outside a castle, fire three to five cannon rounds into it, mow down a phalanx of foot soldiers with a chain gun, then drive off in the direction of the next castle, and word is going to get around. Do that two or three more times, and they'll deliver the crown jewels in a box.

  • $\begingroup$ I was thinking along these lines too. In fact, you wouldn't even need the cannon or chain gun. Just run over a troop of pikemen and you'll be emperor of the world. $\endgroup$ – Michael J. Jan 12 '17 at 21:42

All tanks have manual back up systems. Electronics is not critical. Furthermore, an Abrams will run on anything that burns. As long as the technology is available for a wood or coal engine then the drive train is crappy but replaceable. Cannons are also replaceable.

The real hold back is that there would be no reason. A horse drawn Cannon takes far less energy to move than a tank, which has essentially the same capability against soft targets. Tanks are a luxury and there was no incentive to build them despite being quite readily possible.

  • $\begingroup$ Welcome to WorldBuilding.SE! Please note that the question specifies a modern tank that's been sent back in time, not one that's somehow been built in modern times. So the "no reason" part isn't relevant. Just assume that the tank is there, and that whichever army discovers it intends to use it. $\endgroup$ – F1Krazy Sep 25 '19 at 9:08
  • $\begingroup$ That's what I said $\endgroup$ – user69147 Sep 25 '19 at 15:02
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    $\begingroup$ "No incentive"... ya know, other than the handy feature of not having your cannon operators blown up. $\endgroup$ – ArtOfCode Sep 25 '19 at 17:48

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