I received some site feedback back in July that was interesting. (Sorry to the guy who wrote it ... I started writing this that day but got distracted.)
For reasons I could never quite understand, my opponents have always gone apeshit over a tiny issue. In The Empire Strikes Back and Return of the Jedi, we see some two-legged walkers running around in addition to the big four-legged AT-ATs. We're never told the name of these. In the RoTJ novelisation, they are referred to as "war wagons", "armored vehicles", and "war-machines" . . . in the script, they are "giant", "mighty machines" . . . none of which sound anything like an official designation. And of course, the term "chicken walker" that some have employed was also out-of-bounds.
At some point way back when someone got the bright idea to use a knock-off of the "AT-AT" designation, and so in the EU these two-legged walkers were known as AT-STs. Whereas AT-AT had stood for "All Terrain Armored Transport" per the TESB novel, AT-ST was given the meaning "All Terrain Scout Transport" by EU sources.
But since EU sources aren't canon and my site is based on the canon, the most I could do is what I did: I used the AT-ST term for ease of reference (much as I use Starfleet ship class names never spoken on screen but widely accepted), while accepting none of the non-canon info about the vehicle ... including the phrase "All Terrain Scout Transport".
And as I'd said, "In spite of the non-canon denigration of the vehicles, AT-STs are evidently the premiere small combat vehicle of the Empire, not reconnaissance vehicles or transports (how does one do much transporting in a two-seater?). We have witnessed their frontline combat use at Hoth alongside the larger AT-ATs, and we see them serve as the primary fighting vehicle in the thick forests of the Endor moon. In the RoTJ novelisation, they are referred to as "war wagons", "armored vehicles", and "war-machines" . . . in the script, they are "giant", "mighty machines" . . . hardly terms befitting a mere scout. Indeed, the only scout/recon activity we see is performed on the speeder bikes which suit the role best, and which are piloted by people identified as scouts."
However, since I have a page detailing the weak armor and structure of the AT-ST (or whatever its proper designation in the canon universe), it became very important to my opponents to make the vehicle out to be a 'mere' scout, intentionally fitted with a pitiful papier mâchè hull.
It's silly, but then so are they.
However, I'm told that in the radio play of Return of the Jedi, they are indeed called "scout walkers". Of course, this is the same RotJ radio play that was made about a decade after the film and used EU characters and terminology, so I'm hardly that concerned.
But, I was inspired by the guy to take a closer look at real scout vehicles.
After all, it is true that scouting vehicles have taken many forms, historically. The usual concept of a scouting person is of a quick fellow who is not bogged down by too much equipment, capable of rapid movement and at least a little stealth. Wars of the 20th Century have seen a similar design philosophy behind scouting vehicles. One of the more popular American scouting vehicles of WW2 was the Harley-Davidson WLA, a motorcycle which served with distinction. (I'm guessing they muffled the hell out of it, 'cause these days you can hear a Harley coming from miles away.)
There were also larger vehicles that served in the role of scout, however. A wide variety of armored cars have been used in the role. These heavier scouts are generally multi-role vehicles, capable of performing various duties like cargo transport, armored personnel carrier, command car, ambulance, and so on, sometimes dependent on modifications.
The American M3 scout car resembled the well-known "half-track" vehicles of the era (which were based on the M3 chassis), but with four wheels instead of tank-like treads in the rear. Capable of carrying the driver plus seven occupants, they had 6-13mm of armor depending on location on the vehicle, giving it armor numerically equivalent to the British Mk I heavy tank of WW1. The vehicles saw extensive multi-role use. The M3 was equipped with a .50 cal machine gun and two .30 cal machine guns on rail mounts. During 1943 they were largely replaced by other vehicle types, including the six-wheel M20.
The M20, known as the Armored Utility Car or the Scout Car, was based on the M8 tank destroyer. The turret removed and an open-top rear section added, the vehicles were lightly armed with a .50 cal machine gun but fast, and featured up to 19mm of armor in the front. For armor comparison, note that the basic Sherman tanks of WW2 featured some 50mm of armor on the best-protected upper-front area, achieved in part via armor sloping. The M20s were probably the heaviest scouts of the war, and the crew of up to four were even provided a bazooka for anti-armor use. The additional capacity of the open-top rear section allowed additional cargo or transport ability.
The British Dingo was designed as and often used as a scout. Officially known as the Daimler Scout Car, the Dingo was a 2-seater with 30mm of forward armor protection. They generally carried a light machine gun or, in some theaters, an anti-tank rifle capable of penetrating up to 20mm of armor plate at about 100 yards.
Also of interest is the T-60 "scout tank". Featuring 7-20mm of armor protection and a 20mm armor-piercing main gun with at least one additional light machine gun, the scout tank was a far cry from the Harley-Davidson WLA. Similar to the scout tank were the tankettes . . . small one or two man tanks, often without a rotating turret, designed for infantry support or reconnaissance. These were usually armed with either multiple machine guns or, more rarely, a 20mm cannon or RPG. Most tankettes were somewhat lightly armored, with the Japanese tankettes the best protected with 12mm of forward armor.
For more modern scout car examples, the French VBL is a small vehicle of a jeep- or Humvee-like design, but which was designed as a light armored vehicle with a recon variant. The vehicle has up to 11.5 mm of armor protection. Also in existence is the RG-32 Scout, an unarmed SUV-looking vehicle designed to be survivable against small arms and small mines.
Jeeps and Humvees have also been widely employed in the scout/recon role over the years. Though generally lacking the armor protection of armored cars, their speed and nimble maneuvering make them very good in the scouting role.
On the flipside, we have the British CVR(t) vehicles . . . combat/ recon vehicles, either tracked (t) or wheeled (w) (though the latter never came to much fruition). One such vehicle is the Scimitar, an "armoured reconnaissance vehicle" that is basically a light tank like the T-60 (and often classed as such), featuring a 30mm main cannon capable of firing explosive and armor-piercing rounds at up to 90 rounds per minute (limited by the 3-round clips employed).
From this little survey of scouting vehicles, we can see two or three main families:
1. The "light scout" . . . including the Harley, jeep, and Humvee:
Light, nimble, and quick, these vehicles are designed for rapid travel over whatever terrain is needed. Like human scouts they are not intended for combat or any significant contact with the enemy, but instead to quickly gather information and return safely and with haste. These generally feature little more than the defensive small arms of the crew, and the vehicles are generally just multi-role or logistical vehicles used in the scouting role. As such they have limited armor protection.
2. The "heavy scout" . . . including the Dingo, VBL, RG-32, etc.:
Not quite so nimble or quick as the light scouts, these vehicles are designed with the idea of briefly bumping into small pockets of enemy personnel in mind. Some are armed with light defensive weapons and some are not, but all offer some form of armor for crew protection in forward battlefield or patrol conditions. These vehicles are purpose-built scouts, though other uses may occur.
Included in our informal "heavy scout" designation would be vehicles like the M20 or M3, large vehicles of significant armor protection which featured one or more large machine guns.
These latter vehicles blur the lines between scouts and "battle taxi" armored personnel carriers like the M113, especially given their transport capacity. The M3 and M20 were both used in the APC role. All scouts, like most or all APCs, were not intended for combat against other armored vehicles. Their armament was anti-personnel in nature.
Vehicles intended for combat against other vehicles or positions as well-fortified as combat vehicles are armored fighting vehicles (AFVs) or, if troops are also carried, infantry fighting vehicles (IFVs). Indeed, M3 variants were AFVs, and the M20 Scout Car was simply an AFV with downgraded weaponry.
The T-60 scout tank was definitely an armored fighting vehicle, despite the scout designation. So too is the British Scimitar. These "fighting scouts" make up their own family of sorts. Of course these families are very informal designations, though useful for our purposes . . . and indeed even formalized military classifications feature a great deal of overlap.
Naturally none of these are the heaviest combat vehicles by any means, nor is that the plan. The variations of military vehicles from Main Battle Tank to truck are based on selecting compromises between speed, weight, cargo capacity, armor protection, air transport ability, terrain navigation, and a hundred other things.
Now, let's stop and take a moment to process this information in the context of our subject.
The Imperial military primarily uses walkers for ground warfare. Like tanks and other modern ground vehicles, walkers must observe some mass limits in order to traverse the ground. And, as seen in the forests of Endor, size limitations also come into play . . . though AT-ATs were used, much of the forest could not have been traversed by them without the blasting of pathways.
The AT-ATs serve in the role of main battle tank, with virtually impenetrable armor and the heaviest weapons capable of striking the hardest ground or mobile targets. However, they also have APC capability in the main body, making them a fusion of tank and APC not usually considered workable in modern Earth warfare . . . infantry fighting vehicles (IFVs) don't usually pack the punch of a main battle tank.
The AT-ST is another story altogether.
We could try to pigeonhole the vehicle into any number of classifications.
Let's consider some options, like Main Battle Tank (MBT), Infantry Fighting Vehicle (IFV), Armored Personnel Carrier, and the light, heavy, and fighting scout groups we pondered earlier.
For instance, if the AT-ST had the guns and head of an AT-AT but simply lacked the cargo/infantry-carrying part of the body we could easily think of it as a proper main battle tank. However, it is a much smaller vehicle with smaller, and thus presumably less-powerful, guns.
Further, we've seen that the AT-STs appeared on Hoth only after the AT-ATs had destroyed the majority of heavy weapons emplacements. If this was intentional, then it suggests that vehicles were considered less survivable than the AT-ATs. This could put them anywhere from light tanks on down the line.
We know the AT-ST does not have significant transportation capability, though, implying that they cannot be APCs. And we know they can't be light scouts . . . that's where speeder bikes, AT-RTs, STAPs, and similar vehicles come in. Heavy scouts might be used for fire support of a squad much as the AT-STs were used in RotJ, but as a rule would not be mainline combat vehicles with armor-piercing capabilities, unless it was a heavy scout heavily modded. If anything, what we have in the AT-ST is something like the Scimitar . . . a light tank with a recon role . . . or something akin to a T-60 scout tank or the Japanese tankette.
Indeed, given their battlefield use on Hoth, abilities of armor penetration, and infantry support use, I would argue that AT-ST would best be understood as an acronym for "All Terrain Scout Tank".
Which, coincidentally, happens to satisfy the radio play designation of "scout walker", in concert with the script and novelization statements regarding a giant, mighty war wagon.