How "old" is mechanized infantry in terms of usage in warfare and what should be called as such?

Question

This topic often fascinated me as a kid. I often questioned myself if there was an equivalent of the use of machinery to protect ground soldiers during a siege or an attack at some city or whatever war was involved.

Reading the Wikipedia article for Mechanized infantry, it mentions that Mech inf (for short) are infantry equipped with armored personnel carriers or infantry fighting vehicles and it shows a picture of a M113.

But continuing reading I found that there were other vehicles used for such purposes, such as tanks and hybrid vehicles with ordinary vehicle wheels and caterpillar tracks.

I often thought that the term would be applied only to vehicles similar to the M113 but it looks like this isn't the case. Thus my question arises - if in history of warfare, this concept can be extended to other similar mechanical apparatus used by different civilizations.

Searching my memory, I recall the phalanx formation, or the mythical Trojan Horse. Is this an attempt at mechanized infantry? How about battering rams used in the middle ages? I know in East Asia, Koreans had the Turtle ship and this doesn't count if we consider that what I'm asking moves on land and not by sea. I also forgot to mention Da Vinci's supposed tank (not sure if he did build one) and I also remember James Burke's Connections program mentioning something about Gustavus Adolphus at the Battle of Leipzig during the Thirty Years War: he used men armed with pikes and muskets. But again, I don't think this constitutes a mechanized infantry, maybe just a combined arms operation?

Anyways, when does this concept really began? Is there any evidence of similar things used in the ancient world, middle ages and beyond?. Moreover, during the recent Libyan war in 2011 I noticed rebels used ordinary vehicles attached to guns which the media called "technical" (for those improvised vehicles). Can these be called Mechanized infantry?. What do books say about the definition of Mech infantry used by most NATO countries today?

I hope someone can help me to get a clearer idea of all this.

Answer 1

Mechanised infantry were used in very small quantities during WWI, with extra troops carried in German A7V tanks, and became reasonably commonplace during WWII, with the advent of armoured personnel carriers.

The defining feature of mechanised infantry is that the vehicles they travel in provide a significant degree of ballistic protection. Apart from that, they may be tracked or wheeled, but the ones with heavier armour tend to be tracked. If the infantry can fight from within the vehicle, it is called an Infantry Fighting Vehicle (IFV); if not, it's an Armoured Personnel Carrier (APC), like the M113.

The US uses the M2 Bradley as its IFV and the M113 as its APC, although they make less use of APCs than less wealthy powers. The UK uses the Warrior IFV, and the FV432 APC. Germany uses the Marder IFV, and several different APCs, all wheeled. France uses the AMX-10P IFV and the VAB APC. There are plenty more listed here: NATO doesn't have much standardisation of armoured fighting vehicles these days.

The difference between an IFV and a tank is that the tank is more heavily armoured, armed with a large high-velocity gun intended mainly for killing other tanks, and doesn't have space to carry infantry. All of the crew of a tank are dedicated to operating the tank, while an IFV has a small vehicle crew, often only two people, while the additional people it carries are equipped and trained as infantry.

Motorised infantry travel in vehicles that don't provide protection, such as ordinary trucks, or SUVs. They're much cheaper, but the infantry take far more casualties on a real battlefield. "Technicals" are an improvised example, generally used in low-intensity conflicts, by irregular forces (rebels, guerrillas, and so on).

Mechanised and motorised infantry, as a concept, really date from the first half of the twentieth century. An infantry phalanx is only similar in that it is the most powerful and best-protected kind of infantry of its period. The Trojan Horse was a ruse of war, not a vehicle.

Motorisation and mechanisation gave infantry speed of movement, equal to that of tanks, which had replaced cavalry. You could try to argue that troops who rode horses for mobility, but dismounted to fight, were the predecessors of mechanised infantry, but the analogy is weak.

Answer 2

You might be interested in the Wagon fort (or in German, Wagenburg): including armoured wagons used as fortifications to defend soldiers -- and regularly used as such, tactically, on the battlefield.

A circle of wagons was especially useful against cavalry, apparently.

They're not "mechanized", in the sense that they're not mechanically motorized ... but you must have expected that, when you asked about the middle ages.