What is the benefit of an AT-AT walker over a conventional tank?

Question

AT-AT walkers are used by the Empire in a manner that is tactically identical to how a modern day army would use a tank, in that they are used as shock armour with powerful main guns which will punch through entrenched positions. (No combined arms tactics were used in the Battle of Hoth, but that's a different question altogether)

However, AT-AT walkers have a number of (rather lethal) drawbacks and no advantages that I can see compared to tanks.

1. They have footpads in place of treads, which greatly increase their ground pressure, and which will cause them to easily sink as compared to treads
2. They have a high center of gravity and can be easily tripped, which was exploited in the Battle of Hoth. (granted that this was canonically presented as an oversight, albeit a rather stupid one, since most martial arts strongly emphasise lowering your CG.)
3. They are slower than a modern main battle tank despite their long legs, which one would normally expect to grant additional mobility (max speed 60km/h on flat terrain, compared to 72km/h on flat terrain for the M1A1 Abrams). This is exacerbated by the fact that AT-AT walkers are using fusion power cells as compared to diesel engines.

It would seem that it would make far more sense for the Empire to remove the legs and mount the main chassis on treads, which would make the vehicle far more effective. Why then, did they not do this? It clearly was not the case that imperial Engineers lacked imagination, as they did produce wheeled armoured vehicles.

Possible answers which I find implausible as advantages:

1: AT-AT walkers are tall, and therefore have a surveying advantage over the battlefield / have a better vantage point to fire from

Orbital satellites can provide the observation, and in any case air/orbital support should always be called in, especially if fire support from above is required.

Answer 1

AT-AT means All Terrain Armo(u)red Transport.

It's not 'just' a tank. Primarily its role is to take in its compliment of Stormtroopers to the enemy in safety. (Thus, packing the armour that Luke complains about in Ep. V) (In that sense, comparing the speed of a 4 person Abrams isn't really fair against a 40 troops-worth of AT-AT)

Two main reasons for long legs (apart from movie aesthetics) in universe as far as I'm aware are:

1. Versatility; Vehicles with treads can't just step over small cliffs or other steep changes in altitude. The AT-AT can.
2. Artillery; Projectiles are subject to gravity, thus to shoot far away a tank would fire upwards so the projectile will arc down and hit its target. However, lasers in the Star Wars universe aren't affected by gravity. Thus, the higher the vantage point, the further you can shoot.

But, mainly, it looks badass (as Richard pointed out earlier in the comments).

Answer 2

Clearly speed is not one of the AT-AT's assets. They're also lumbering & they shake the ground from a considerable distance as they walk. Therefore we can say that surprising or surging towards an enemy is not one of the AT-ATs intended attributes. If it were, a faster wheeled method of locomotion would clearly be preferred. From what we've seen they're susceptible to revealing their presence early & then taking quite a while to get within range to engage their target (as was the case during the Battle of Hoth). So their purpose seems to be very different from that of a more nimble wheeled attack vehicle like a tank.

What seems likely is that they're built for "shock & awe". It was established that the Empire employed fear as a means of control. The AT-AT's size, offensive weaponry & the way they look all seem designed to scare & intimidate. The giant creature design & the "walking" that literally causes the enemy to tremble would seem to be an important part of this fear objective. As has also been pointed out they're used to transport troops. They are an Attack Transport. A tank does not fall into this category so therefore they don't offer an alternative if transporting a large squad of soldiers is one of the objectives.

A more appropriate comparison with a tank (though a moderately armored one) is the AT-ST. That's the smaller two legged Walker. Like a tank it's faster, more maneuverable & cannot carry a large number of personnel. The on screen evidence suggests an Imperial ground assault features the AT-ATs while also being supported by AT-STs. We see at least one AT-ST on Hoth & several on Endor. Since both of these vehicles have different strengths & purposes I think we can conclude that they're meant to work in co-operation & there are great advantages to each vehicle in doing so.

So in answer to your question, the Empire employed very large (& highly destructive) armored transport vehicles (AT-ATs) supported by smaller, faster & more maneuverable "tanks" (AT-STs). As for the walking aspect, I see the advantages from a practical in-universe perspective as:

1. An elevated vantage point for the pilot & crew.
2. Lifting the hull above hazards such as water or jungle. This also allows the weapons to operate without interference in these situations.
3. As part of an overall fear & intimidation design objective.

Answer 3

The AT-AT is superior to the M1 Abrams tank in every way except speed. It boasts a greater range of environments, longer operational time, supports and carries troops and light vehicles, can devastate almost any type of fortification, immune to all but the heaviest artillery fire, and capable of working across almost any terrain, rocky, forested, snow or desert.

• Designed to be impressive, its nearly-indestructible durasteel body and signature sound profile on the battlefield demoralizes enemy troops before it can even be seen. Capable of moving 40 kph, it isn't very fast but with its KDY FW62 compact fusion drive systems it can operate indefinitely in the field without needing to refuel.

• Armed with advanced bunker-busting weaponry, the AT-AT is designed to attack any kind of vehicle or fortification and destroy it. Its great height allows it to target objects at the extreme range of their weaponry. Using blaster technology, the AT-AT does not have to carry ammunition utilizing the energy of its nuclear powerplant. This means there is no potential for ammunition mishaps nor the threat of running out of ammunition.

• Functioning as a troop transport it can move men in complete safety within its durasteel hull, ensuring their arrival on the field of battle. It can carry 40 troopers and their full combat kit. As an alternative, the AT-AT can carry five light speeders and their pilots.

• It can also provide troop support and covering fire with its two swiveling medium repeating blasters. Its height gives field commanders a superior view of the battlefield while keeping them safe to coordinate the battle without fearing for their safety. A major asset in any military operation.

• The AT-AT can also operate in shallow bodies of water without fear of compromise and can be altered to work in a variety of other environments, extreme cold or heat, forest or desert conditions do not appear to hamper their movement. Rocky terrain may slow their approach but does not stop them from utilizing it. However a steep grade may require a skilled pilot to use the device effectively.

Limitations of the AT-AT

• The greatest limitation to the AT-AT is its lack of mobility. Its relatively low top speed and difficulty changing direction means it has to be moving toward its target and it has a relatively small arc of engagement without turning its entire body.

• In comparison to a tank with its swiveling gun turret a tank can change direction and fire in a completely different direct at the same time.

In favor of Tanks

A tank has several powerful assets working in its favor.

• It is fast and mobile. The M1 can go from 0 to 20 mph in 7 seconds. With an operational speed of 35 mph and when properly configured with reduced armor, capable of reaching a top speed of 60 mph (though certainly with a further reduction in gas mileage.)

• A tank brings a considerable amount of explosive firepower in low to the ground, compact form, avoiding damage when possible, but able to handle a good degree of damage before becoming inoperative.

Photo courtesy U.S. Department of Defense

However:

• A tank can be hampered by terrain, its human crews can also be affected by environmental conditions. While their treads allow them to navigate most firm terrain easily, mud, water and extremely rocky conditions slow them considerable.

• The M1A1 (I chose it due to its overall superiority in operation) requires a significant fuel supply (even with its digital engine technology, the M1 gets about 1 mile per gallon!). To offset such low gas mileage, tanks have giant fuel capacities, capable of carrying 490 gallons of fuel and being able to travel about 265 miles before needing to refuel.

• Tanks use physical ammunition for its weaponry. With its sophisticated fire control it can fire and move at the same time. Other tanks have to come to a complete stop to reliable hit anything. Tanks carry sabot and HEAT rounds.

• Lightly armored M1s can also be affected by man-portable weapons such as RPGs or TOW missiles. The heaviest armored ones can survive more than one hit from even another tank but are vulnerable to powerful weapons like the Hellfire missile.

The tale of the tape says:

AT-AT or Imperial Walker

• The AT-AT is a more versatile, hard-hitting and troop transporting vehicle capable of working in a variety of theatres.

• Its weapons are formidable and aided by being higher off the ground. Once AT-AT reaches the target, the AT-AT superior weaponry ensures nothing can resist it for long.

• Its biggest liability is its lack of serious speed and limited arcs of attack. It needs other smaller vehicles to protect and support its bulk from small and fast vehicles which may attempt to entangle its legs to topple it.

M1A1 Abrams Tank

• While the M1 is a powerful weapons platform and has performed admirably under field conditions, it cannot compare to the AT-AT in terms of range of operations (its low gas mileage is a killer) though its top speed and agility get the highest marks.

• The AT-AT is far more durable and resistant to weapons fire, and some terrains are less hospitable to treads than the ambulatory motion of the AT-AT.

• The tank's ability to attack and move in multiple directions is a great asset and such mobility is key to dealing damage while avoiding being damaged.

• Its need to be resupplied means its longevity in the field is dependent on whether supply lines are available to replenish fuel and ammunition, of which neither are used by the AT-AT.

Winner: AT-AT for extreme durability, damage-dealing capacity and troop transport and protection.

Answer 4

Most conventional vehicles in the Star Wars universe, including tanks, use repulsorlift technology. Repulsorlifts have many advantages over standard wheeled/tracked vehicles such as (limited) vertical movement and being unhampered by most terrains (an Abrams, for example, will sink in water. The modern-day hovercraft, the closest thing we have to a landspeeder... won't). They also don't trigger pressure-sensitive land mines, such as the kind we use today.

Walkers, including the original AT-TE, were developed in response to anti-repulsorlift mines, which most conventional vehicles in the Star Wars universe were vulnerable to;

Walkers - These military vehicles were developed in the early days of the Empire in response to repulsor-oriented land mines. Similar developments were used to augment existing repulsorlift, crawler, and wheeled vehicle designs.

Wizards of the Coast: the Star Wars Roleplaying Game, first edition - p. 165

The long legs of a walker, despite the drawback of a high center of gravity, actually provide a number of benefits. For one thing, the lack of armor on the underside of the vehicle is no longer a problem as the underside is well out of range of the explosive radius of any mine, and the legs are heavily armored enough that even going back to a standard pressure mine won't do much good; also, the relatively small footprint (pun intended) of the vehicle means that mines would have to be packed relatively closely together in order to ensure that the walker even stepped on one.

Another benefit is that the walker isn't really hampered much by the terrain. Smaller vehicles would have to go around (or get stuck in) the kind of terrain that a walker could just step over/wade through (including trees, unless they're the kind of trees that a forest world like Endor or Kashyyk would support. You'll note that we only really saw one AT-AT on Endor, and most of the troops there used the smaller, more maneuverable AT-STs).

Third, as previously mentioned, the AT-ATs were heavily armored. Vehicles are a trade-off between speed/maneuverability and durability; the walkers sacrificed the former for the latter. AT-ATs were able to carry the kind of armor that would make a tank too heavy to move, and the kind of guns to match.

And actually, the high vantage point was more of an advantage than it initially appears, not so much for simple visibility but more the fact that the forward-mounted guns themselves were at a height that made it less necessary to fire arced shots or artillery shells (assuming blaster technology was better than artillery against armor, blaster bolts travel in a straight line); simply point and shoot. The AT-AT comes with its own built-in "high ground" advantage.

And yes, they were essentially heavy troop transports.

So ultimately, you have a vehicle that can shrug off most normal weapons fire, isn't vulnerable to the most widely-used area denial tactics of the era, can rain direct-fire death down upon your troops, has all of the advantages of terrain movement that repulsorlift vehicles did, and once they do eventually get where they're going, will drop a horde of Stormtroopers on you. Sure, they had weaknesses, but note that until Luke came up with the idea to use the tow cables, the Rebels were getting slaughtered.

In short, AT-ATs were tanks, artillery, and APCs all rolled into one. In shorter, walkers had advantages over repulsorlift vehicles, which in turn had advantages over 'modern' military vehicles like the M1A1.

Answer 5

Yes, given the same resources, the Empire could build a far more effective vehicle than the AT-AT that would be faster, more manoeuvrable, able to handle tougher terrain (particularly soft terrain), more stable, easier to control, better protected, and stealthier while providing the same or better firepower and payload by using tracks, wheels, or repulsors rather than legs.

There are also far more effective ways to get height for visibility than lifting the entire vehicle on long legs such as a telescopic mast or a drone.

The only reason I can think of to use the AT-AT is that it might have some benefit in being intimidating in much the same way that in Stargate SG-1 the Goa'uld built their weapons to intimidate their primitive human slaves rather than for maximum effectiveness as weapons.

Other than that, it's pure rule of cool. Giant walking war machines are just cool despite being inherently impractical. They are cool but impractical in Battletech, cool but impractical in Macross, cool but impractical in Gundam, cool but impractical in Evangelion, and cool but impractical in Star Wars.

Answer 6

Advantages:

1. Looks way cooler.
2. Sounds cooler. (PewPew, PewPew, PewPew)
3. Lucasfilm could copyright and market figurines.
4. Able to handle slightly more variations in terrain since it has legs, but loses swampy terrain for the same reason.
5. Elevated position provides excellent field of fire.

Disadvantages:

1. Balance
2. Slow
3. Height

Bottom line, build a crawler (shorter with 6 legs). Use the same weapons and armor. See Clone Wars. Or build a tracked tank with durasteel armor and pulse laser weapons.

Another comment mentioned "Big Dog", for which DARPA is funding research. Big Dog is not comparable to a tank or an AT-AT. Big Dog is literally the size of a big dog. It has a comparatively (comparing to AT-AT) low center of gravity. Big dog is not armored and has no weapons, it only carries equipment so the soldiers are more lightly encumbered and able to move further and react faster.

Answer 7

Based on the information on the Star Wars Databank (considered a canon source of information about the Star Wars universe is), the main advantage of an AT-AT is the height of the vehicle as well as its awe-inspiring size.

The All Terrain Armored Transport, or AT-AT walker, is a four-legged transport and combat vehicle used by the Imperial ground forces. Standing over 20 meters tall with blast-impervious armor plating, these massive constructs are used as much for psychological effect as they are for tactical effect.

As to their tactical advantage, can a treaded vehicle do a jump like this?

_{^{Star Wars : SP:FX - The Empire Strikes Back}}

Answer 8

As good as turbo lasers are, they don't arc like traditional tank rounds. Any low slung earth works would be a strong defense against a laser carrying tank. We can put the weapons up on a mast to give them that shoot over the walls height but then they are easy targets as their mast could be easily severed by defensive fire. Also rough terrain would be amplified by the length of the mast, so you wouldn't be able to shoot while moving. The legs provide a stable, well armored firing position of the height that their weapons need.

Answer 9

Building on Richard's answer, "tank shock" or equivalent psychological tactics (as from calvary charges, war elephants, etc.) have proven quite useful historically. And, given the Empire's tendency to employ weapons of dramatic/outlandish scale, the creation of the AT-AT makes perfect sense.

(Source: Henry-Paul Motte via Wikipedia)

Their height is also an advantage when crossing swamps, rivers and lakes:
(Source: All Terrain Armored Transport @ Wookieepedia)

Tanks are low to the ground to minimize their profile and make it easier to take a hull-down attack position. Since AT-ATs are mostly invulnerable (except when attacked from directly below, which is mitigated through armor formations), it makes sense to simply capitalize on the intimidation factor and better vantage point.

As other answers have alluded to, an AT-AT can simply fire down into bunkers, taking the place of artillery and even ground attack aircraft.

Lastly, the AT-AT isn't really an alternative to an MBT. That would be the AT-TE:
(Source: Wookieepedia)

Answer 10

You have to remember that the Empire uses the "right tools for the job". They are not stupid. In the only instance that we see an AT-AT in combat, it is for a VERY specific purpose: ground assault THROUGH A SHIELD GENERATOR.

Bear in mind, the shield generator repels repulsorlift vehicles, making it impossible for them to pass through the shield (same with air forces, which is why there is no air cover during the Hoth assault). However, the AT-ATs, being a walker vehicle, has no such limitation. In addition, being a heavy troop tansport AND an assault vehicle, their use on Hoth makes perfect sense.

Are they the correct vehicle for every situation? Of course not, just like there are times to use Hum-vees and times to use tanks. You don't send an APC into a fight with a main battle tank. However, for the battle of Hoth, they were the right vehicle at the right time.

Now, as to the benefit of a walker over a tank, there are a couple of reasons (the other answers here do an admirable job of addressing those). But I just wanted to point out that there are instances where, even if tanks had more benefits overall, in THIS INSTANCE, the AT-AT was the right choice.

Answer 11

AT-AT's shoot lasers and their range is limited by line of sight, unlike a tank's ballistic trajectory. So the AT-AT would have to be taller to shoot as far as a tank.

Answer 12

While the AT-AT is more superior to the tank in many aspects the simple thing I see is that that even with the Empires wealth they could have easily made it more versatile while keeping all its benefits. If they added anti-air turrets on the top and sided of the walker with the ones on the side capable of targeting ground troops. Or even some massive barrage cannons in the sides. They would be more of an assault weapon instead of an armored bunker buster with very obvious weaknesses. They are definitely large enough and could be install with the large space inside making it more viable for fighting more than just bunkers and entrenchments but also allowing it to defend itself against bombers, tow hooks, and one 'jedi' with a grenade and grapple gun....

Answer 13

It is possible the purpose of legs on the walker is to handle water and deep snow which it would have the advantage over tanks. On Hoth snow can easily be several feet deep and armored vehicle regardless of there size have trouble moving through snow as snow does not always pack hard so if a tank went from rock to snow it would have a high chance of getting stuck or in reverse went from snow to rock could not move past the rock because the elevation makes it impossible to ascend snow would give way not allowing treads to have tracks. walkers might be slow but they can handle environmental conditions and terrain that sick and give way to constant contact like treads. Not just snow swampland and rivers are impassable for tanks depending on debt. walkers are tall so maybe they are also design to be stationed in the middle of lakes they are also fully sealed and capable of going into the vacuum of space and deep into water something tanks are not designed for. The feet of walkers are also magnetized and have the ability to clamp onto extreme inclines for some climbing ability treads have not stationary hold so a tank can be flipped in a rock slide or avalanche which has happed before. I think mainly the walker is designed for terrain that sinks. Tanks are normally not deployed in areas of the world with swamp terrain like south America in the depts of rain forest a tank would never be able to get through cloud forest or rain forest. If you want another Sci Fy answer to this look into the Metal Gear Solid series and they go into great detail the need for a walking tank versus a treaded tank in some cases.