Tanks are one of the most well-known weapons of war. But, after over a century of roaming the battlefields of the world, could small and cheap drones finally put an end to the "age of the tank?"

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Tanks first appeared during the height of the First World War, where they were designed, in part, to break the stalemate of trench warfare. While developed simultaneously by various nations at the time, it was the British who first put them into action at Flers-Courcelette during the protracted  Battle of the Somme in 1916.

Assigned to the New Zealand Division on the Western front, four Mark 1 "Male" tanks were tested under fire and were found wanting. While they did manage to advance around a mile or so into enemy lines, they were far too slow to hold their position and were quickly overrun. 

These early tanks were notoriously unreliable and often broke down or got bogged down in the ruined landscape. It wasn't until large numbers had been built and could be deployed en masse that the true power of these land battleships eventually became evident. 

The lessons learned from these early uses of tanks were quickly adopted by all the major world powers, and tank designs would become increasingly more complex, reliable, and powerful over time. By the time of the Second World War, some developed tanks would emerge, earning a formidable reputation for decades to come. 

The "age of the tank" had finally arrived.

But during the Cold War, some in the military feared this situation would not last - according to some military historians. The advent of anti-tank guided missiles, ATGMs for short, was believed to herald the end of tanks as a major weapon of war from the 1950s onwards. However, as we know all too well today, tanks are still critical to modern combined armed forces. But why? 

Put simply, when you have a hard nut to crack, like a bunker or dug in opposition, you need tools like tanks to breakthrough. But, just like in the past, tanks are not a panacea for a military problem. They are vulnerable on their own and require infantry, artillery, and air support. Without it, tanks can and will be killed en masse.

You can get a sense of this from films like the 2014 film "Fury." While this is obviously heavily dramatized, the role and vulnerabilities of tanks are fairly well shown. But even with this kind of support, tanks are often knocked out by a technologically equal opponent. 

Take WW2, for example. Tens of thousands of tanks were produced by all armies involved in the war. This was, in part, to replace lost, broken down, or captured tanks across various theatres of the conflict.

Put simply, during large-scale conflicts, tank commanders and their superiors expect heavy losses from their tank divisions. It is something of an occupational hazard - after all, tanks will attract attention on the battlefield. 

To give you an idea of the scale of the losses during the Second World War, the British lost somewhere in the region of 15,880 tanks throughout the course of the war. For the United States, something like 10,000 was lost as part of their part of the war. Germany lost around 67,400 tanks and self-propelled guns, and the Soviet Union suffered horrendous tank losses, with some estimates in the region of 83,500.

For all forces, "lost" tank figures don't necessarily mean they were knocked out by enemy fire but, rather, were also deemed irrecoverable (i.e., beyond repair or no longer serviceable). 

That is a lot of armor. And, of course, a lot of people. And the problem still exists in our more modern times, as in Ukraine, where Russian tanks have proven vulnerable to drones and even to being towed away at night. However, the tank is still deemed a valuable asset to modern militaries. 

One of the more recent examples is NATO's involvement in Iraq and, to a lesser extent, Afghanistan. Initial invasions and battles showed the value of the firepower provided by tanks.

However, the war once again revealed the vulnerability of their expensive assets when the conflict became more about dealing with insurgencies and so-called "asymmetrical" warfare. Rocket-propelled grenades (RPGs), improvised explosive devices (IEDs), etc., can be fielded very easily against unsuspecting armed forces, no matter how well-armed and armored they are.

Another critical benefit of tanks is something often overlooked - they help inspire the troops. These huge chunks of metal are often seen in a similar fashion to cavalry units of old, offering important morale boosts for beleaguered troops when they are in a fix. The value of this cannot be ignored. Of course, the loss of such units can also have the opposite effect on troops, but this is true for any military asset. 

This doesn't necessarily show that tanks are obsolete - quite the opposite. While they may not be the right tool for the job when it comes to counterinsurgency actions, they are one of the best things available for providing heavy mobile support (if suitably supported). 

To give you another analogy, battleships (prior to the advent of the aircraft carrier and long-range fighter jets) ruled the seas for several decades. While innovations like sea mines or torpedoes could readily knock them out, nothing else came close to the kind of heavy artillery support battleships could provide. 

It was not these innovations that ended the dominance of the battleship but its effective replacement with aircraft carriers. These could provide a similar role and more, meaning battleships were effectively now a dead-end, technologically speaking. 

While some did continue to serve navies until the 1990s, such as the USS Missouri, their role hand changed considerably from their original intent. The same might well be true for tanks.

Like a heavily armored and armed zombie, the tank has managed to weather many challenges and adapt itself to different roles over time. This is unlikely to change in the near future, even with the threat that drones offer. 

So far, tanks have managed to overcome many technologies specifically designed to take them out. But is the latest challenge, that of low-cost and unmanned drones, a step too far for this venerable war machine? 

Let's first address how drones are used to attack and destroy tanks. 

One basic method is to equip drones with gravity bombs or turn the drone into a miniature kamikaze-like weapon. Since they are relatively small, such drones are able to sneak up on unsuspecting tanks and hit them when they might be most vulnerable. 

For example, in 2017, there was the now-infamous example of a drone dropping a small explosive device on an Iraqi tank and killing its commander while he stood exposed in the tank's open hatch. 

In addition, drones are becoming ever more sophisticated over time. In Ukraine, drones like the Turkish Baykar Bayraktar TB-2 are getting a lot of headlines, and for a good reason. 

Small, relatively cheap (when compared to a tank), and easy to use, these drones are effective against Russian armor throughout the besieged country. 

According to a candid interview, Ukrainian drone operators equip a variety of drones with weapons like anti-tank grenades (like the Soviet-era RKG-3) and Molotov cocktails, strike at night, and drop the ordinance on top of the tanks under cover of darkness, before anyone sees them coming. As we've seen from media footage of the armed conflict, this appears to be very effective. 

While anti-tank grenades are generally considered obsolete, this is primarily due to the way that they are conventionally used, i.e., by being thrown or deposited on the tank by getting in close. Molotov cocktails, however, are still very effective against armor because they can either injure or kill the crew directly (if you can get one inside the tank), or can knock out the tank's engine.

To do the latter, Molotov cocktails are generally thrown towards the back of the tank where the engine is located. Since this part is armored, it will also have vents and air intakes that can readily be exploited by the highly combustive liquid making up the cocktail. Successful hits will stop the engine and usually result in the tank crew abandoning the tank. 

While the tank isn't destroyed, per se, it is effectively out of the fight. There is little defense possible against such attacks (unless non-combustion engines are installed), so this is why adequately supporting tanks is vital in combat. 

With the aid of technology like the internet connection provided by Elon Musk's Starlink, this strategy is helping Ukrainian forces punch well above their weight. 

The Turkish drones, on the other hand, are far more aggressive pieces of kit, able to deploy anti-tank missiles from above. With a wingspan of 472 inches (12 meters), these unmanned aerial vehicles are able to carry up to four laser-guided bombs to the enemy. 

Each cost around $1 million, has a range of 93 miles (150km) and can loiter in the air for more than 24 hours. This gives them almost unparalleled abilities to hide and ambush enemy armor with near impunity. 

Another type of drone being used by Ukrainian forces is the American-made AeroVironment Switchblade 300 and 600. These drones are small enough to be carried by ground personnel and are launched using a ramp in a similar fashion to conventional mortars. 

The 300 and 600, as the names suggest, vary in size and payload, but both have a wide range and loitering capability. The 600 variant, being larger, is designed to attack more heavily armored targets, like tanks, and is used in the suicidal, kamikaze-style attack on a potential target. 

It carries an ATGM warhead based on the FGM0148 "Javelin" anti-tank missile and can be set up and launched in less than 10 minutes. These units cost considerably less than dedicated anti-tank missiles and come with the added advantage of allowing an operator to be at a safer distance when deploying when compared to handheld anti-tank missile launchers.

For conflicts like in Ukraine, if other weapon platforms are knocked out by conventional anti-aircraft weapons, their relative cheapness allows them to be deployed en masse. When such a relatively cheap piece of kit is proving to be more than a match for multi-million-dollar machines like tanks, the outcome of such a head-to-head may well turn into a battle of attrition, or depend on how deep the pockets of either side are. 

So, what potential ways could the tank adapt to the threat of drones and anti-tank weapons?  

One of the main threats to tanks on the modern battlefield, as has been made abundantly clear in Ukraine, is, unsurprisingly, the threat of anti-tank missiles and other specialist projectiles. But, rather than just cowering away or never deploying them, tanks have evolved to attempt to counter this very series threat. 

Traditionally this has consisted of simply adding more and more armor to the tank's hull, but there is obviously a limit to this approach. The tank, at the end of the day, does need to be able to move. 

However, the average weight of tanks over the last 100 years or so has more or less quadrupled. One of the first tanks, the British WW1 "Little Willie", weighed in at around 16.5 tons. 

A modern main battle tank, like the American M1 Abrams dwarf tank, comes in at around 70 tons, give or take. On a modern tank, most of that weight is armor plating. 

As you are about to see, while specialist armor plating is one option, modern tanks do have some tricks up their sleeves to help improve their combat survivability. 

So, what options do modern tanks have on offer? 

In the 1970s, anti-tank missiles became even more sophisticated, with NATO forces, in particular, developing systems specifically designed to knock out Soviet tanks from a distance. To combat this, the Soviets invested heavily in finding potential countermeasures to this, leading to its active protection system, or APS for short. 

These kinds of systems include a range of sensors, usually millimetric wave radars, placed in strategic places on the tank to monitor and track any incoming missiles. Once a threat is detected, the system then launches a little missile of its own to intercept and destroy the threat at a distance. 

These systems have proven effective and have the added benefit of being relatively lightweight. They also happen to cost less, on average, than simply slapping more armor plating to the tank. 

One of the most modern examples is Russia's much-touted ARENA system. This was developed by   KB Mashinostroyeniya Design Bureau and is widely considered to be a highly effective countermeasure system.

ARENA is able to detect incoming missiles about 50 yards range from the tank and has a reaction time of around 0.7 seconds. Common anti-tank rockets and missiles, like the Russian RPG-7 or American TOW travel somewhere in the region of 300 yards per second (274 m/s). 

This is fast, but not fast enough to avoid being intercepted. Since human reaction times are nowhere near capable of dealing with this threat, ARENA comes with 22 to 26 interceptor explosives that it can deploy on its own. Once a threat is detected, the explosives are launched and intercept the incoming round at a distance of about 10 feet (roughly 3 meters) from the tank. 

One drawback is that the ARENA is not very effective against weapons fired from buildings and rooftops and has a kill zone of around 20 to 30 meters around the tank - meaning that friendly troops need to keep well away from the tank.

Russia is not the only country to have developed these kinds of systems either. Israel, for example, has its own version called "Trophy." South Korea are arming their K-2 "Black Panther" tanks with their own domestically developed version as well. America, for its part, is also testing its own APS for its frontline Abrams tanks and Bradley infantry fighting vehicles.

A less technologically sophisticated adaptation of tanks is something called reactive armor. This comes in a range of forms, but one of the most common, explosive reactive armor, effectively works by disrupting an incoming projectile's ability to fully penetrate the tank's armor. 

This, after all, is the purpose of most anti-tank weapons (tanks shells, RPGs, or otherwise) — to penetrate the tank's armor and either disable the crew or the tank's internal systems, or both.

With explosive reactive armor, the tank's armor plating includes some form of explosive between the armor plates to make a kind of sandwich. When an incoming projectile hits and penetrates the outer plate, the explosive within reacts, expanding the armor and disrupting the original path of any penetrating element of the projectile.

Where this works, the anti-tank projectile is effectively deflected away from the shell of the tank. While this kind of armor has proven effective in the past, it is not foolproof. For example, it can be defeated by directing several projectiles to the same part of the tank, effectively triggering the defense mechanism, leaving that part of the tank vulnerable to further attack. 

This kind of armor also proves to be less than useful for any close-in "friendly" units, like infantry, that can be caught in the blast radius of the armor. 

Such armor is very popular with militaries using Soviet-era tanks and can be found as an option on U.S. tanks which can be equipped with so-called "Tank Urban Survivability Kits."

Another kind of reactive armor is non-explosive, or non-energetic reactive armor (NERA). Unlike explosives, this armor consists of a series of composite plates that replace the explosive with multiple layers which incorporate ceramics or other nonmetallic materials, as well as steel.  Like reactive armor, the purpose is for the inner lining to attenuate or absorb as much of the impact energy as possible from a projectile in the hopes of limiting the damage to the tank. 

While less effective than reactive armor, NERA is also less dangerous for friendly units - very much something of a compromise. 

The most common type today is something called "Chobham armor", first developed by the British for their experimental FV 4211 tank (a Chieftain tank derivative). 

This armor proved incredibly effective against high-explosive anti-tank (HEAT) projectiles. 

It is this armor that gives the modern US M1 Abrams and British Challenger tanks their characteristic "slab-sided" appearance. 

Another modification tanks have undergone in recent years is the integration of heavier, thicker, and tougher armor. Consisting of plates of heavy metals, like depleted-uranium alloys, this kind of armor is less about sophistication and more about making the tank as tough to crack as possible. 

This kind of tougher armor plating was developed to counter advanced late-Soviet-era kinetic penetrating munitions like the 3BM-32. 

Such armor plating usually comprises either tungsten (as in the British Challenger 2), a mesh of depleted uranium encased in steel (as in US M1 Abrams tanks), or titanium carbide.

All is well and good, but this armor does have one major downside - it is very heavy. For this reason, adopting this form of armor comes with a compromise. 

More weight will affect not only the overall performance and endurance of the tank but can also be costly to produce, install, and replace/repair in combat. 

For any student of war, or anyone closely watching the war unfold in Ukraine, you are probably more than familiar with the cage-like attachments on some modern armor. This armor is called slat armor (also bar, cage, or standoff armor), and it is a relatively technologically simple strategy to help protect tanks from some forms of anti-tank munitions.

A relatively old technology, it is still fairly common today. 

Designed to counter HEAT anti-tank weapons, this kind of armor consists of a rigid, grid, or cage-like structure that is directly mounted to the hull of a tank. The armor works by disrupting the shaped charge of HEAT warheads by either crushing it, preventing optimal detonation blast forming, damaging the fuse of the warhead, or outright preventing detonation in the first place. 

This kind of armor is most effective when the cage spacing is less than the diameter of the incoming warhead. 

Traditionally mounted to the "softer" sides and rear of a tank, Russian tanks in Ukraine also appear to have been modified with turret-top mounted canopies of slat armor too. According to some military experts, these modifications appear to be something of a trial-and-error exercise to find a more cost-effective way to protect the vulnerable tops of tanks from drones and arcing anti-tank missiles.

Some modern anti-tank missiles, like the FGM-148 "Javelin", are able to arc the missile steeply upwards before plunging down onto the top of the target in much the same fashion as plunging shots which proved deadly in "big gun" maritime battles. Since this is usually the thinnest part of the tank's armor, it is a good bet that a direct hit here will be able to penetrate and knock out the tank in short order.

Whether side or top-mounted, slat armor is designed to trigger an explosion from an incoming projectile to occur earlier, deflecting the energy away from the tank. 

All good in theory, but this kind of armor is designed to defend against more common, and older, munitions like the very common RPG-7.  "Javelin" missiles, and other modern anti-tank missiles, tend to consist of two-stage tandem warheads with the main fuse situated to the rear of the warhead. This enables these weapons to defeat spaced and reactive armor, maximizing their penetrative capabilities. 

Considering the number of Russian tanks, many with the slat-armor modifications described above, apparently being knocked out in Ukraine, it appears this strategy is less than foolproof. Some experts even believe that causing an earlier detonation, even one half a meter to one and a half meters away from the hull could increase the penetration of the warhead. 

However, for munitions like kamikaze drones or gravity bombs, slat armor should provide adequate protection. 

A newer form of tank armor is something called "electric armor." It was initially designed to help personnel carriers to counter rocket-propelled grenades (RPGs) and other "shape charges" by deflecting the  

As the name suggests, this armor consists of two or more conductive plates separated by an air gap or insulating material. 

This composite structure turns the armor plating to the tank into, effectively, a powerful capacitor. When operational, the armor is supplied with a high voltage from a power source. 

When the armor is hit by a projectile, the circuit for the armor is effectively broken, leading to a massive discharge of electrical energy at the point of impact. This discharges the armor, resulting in the penetrating munition either being completely vaporized or turned into high-energy plasma, effectively tempering the impact and saving the tank.

While technical details of this kind of armor are usually top-secret, it is yet to be installed on armored vehicles en masse. For example, the People's Liberation Army of China is reportedly developing this kind of armor for their tank divisions. 

The UK is also allegedly developing this form of armor called a "Pulsed Power" system and the United States is also developing a variant of this armor that has been tested relatively successfully on their Bradley Fighting Vehicles. 

One potential option for future drone defense on tanks could be the development and incorporation of direct-energy defense systems. Whether using laser or microwave energy, such systems could be used to target, confuse, or outright destroy unmanned aerial vehicles before they become a clear and present danger to something like a tank. 

It could also theoretically be used to target and destroy incoming munitions.

One current example is in development by General Dynamics Land Systems. While technically being developed for integration on General Dynamics' Stryker vehicles, there is little really stopping it from being modified for Abrams main battle tanks. 

After all, General Dynamics Land Systems also build those. 

For the project, General Dynamics teamed up with Epirus to use the latter's Leonidas high power microwave-directed energy weapon as a short-range air-defense (SHORAD) platform.

This system would be mounted to a trailer towed behind a Stryker (or MBT) to provide an on-the-ground anti-drone aerial defense. Testing of the system has proved very encouraging, with it being able to target and destroy multiple drones or individual targets in short order.

If fully developed into a working system, this kind of add-on could prove invaluable for many tank divisions around the world. 

So, is the tank's day numbered? 

For the short- to medium-term, probably not. Until, and if, some remotely-operated vehicles can be developed that are capable of shielding infantry in close quarters and also provide heavy support, it is unlikely the tank will be retired. Put simply, modern ground armies' combat strategies are based, in part, around the capabilities of the tank, and until it can be replaced with something better, little, if anything, will change. 

But, that is not to say that tanks can "rest on their laurels." They must adapt or face extinction, like any military technology. 

This will likely be a mixture of developing offensive and defensive technologies to counter new threats like drones, but other changes will likely also come in the way that tanks are fielded in combat. For example, they are not the best tools for fighting counterinsurgencies and are very vulnerable in built-up, urban areas with dug-in enemies. 

For this reason, the military doctrine will also adapt over time too. It may even be the case that new support vehicles, possibly remote-controlled, could be developed to help support the tank, as they support infantry in turn. This would be especially the case for dealing with overhead threats to tanks. 

If not, and tanks are retired, it will likely lead to unforeseen circumstances like the greater loss of unarmored ground forces and infantry. This would be ironic, in a way, as this is exactly what tanks were developed to prevent in the first place. 

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