Second tactical update:
In the Tau language the words for hunter and patience are deried from the same root. This technique is the oldest of the Tau technique and has the most variations. Essentially, the technique relies on the interaction of the hunter and the lure. In recent times, auxilliary troops such as Kroot are used as the lure, although some septs still regard the role as one that honours both hunter and prey and allow only bonded Fire Warrior teams to undertake it.
The lure's role is to expose itself to the prey and draw it into a position where it can be killed by the hunter. The more subtle commanders have been known to use the absence of troops as a lure. Once the prey is in position, the lure is free to escape or help the hunter as the situation dictates. Hunters are freuqently equipped with Crisis,Stealth, or Broadside armour with weapons carefully selected for the particular prey.
Again, there is nothing wrong with this concept in theory.. as long as the enemy plays along and doesn't spot the trap (orbital sensors, ground sensors, psykers, etc.) The trap is pretty useless if the enemy won't cooperate. And it probably is useless against an enemy on defensive (it relies on an enemy being on th eoffensive.) This can depend on equipment, commanders/officers, and even specific forces.
The Tau I believed used this strategy against hte Vostroyans in "Cities of Death" and it worked quite well. (although only after they tried shelling the fuck out of their prepared position, and proved incapable of budging them out easily from the position they'd held.) And even then the Tau outnumbered the Vostroyans quite a bit.
Tau do not hold positions by choice. Defensively, the Earth Caste construct bunkers and fortifications to provide shetler from long range or aerial bombardment. Sometimes they construct a hidden bunker or Run'al to allow close observation of the enemy. Neither are intended for static defence.
?? The Tau don't consider bunkers and forts to be "Static" locations or "holding" a position? You cant take those with you, and sticking in one spot nullifies mobility. Against enemies whose bombardments can be massive (like the Guard), this could conceivably pin you in place for a long time. Nevermind anything like orbital or aerial bombardment. Especially if its NOT "by choice"
In fact those are the kind of bombardment the Guard excel at, and its one reason they use bombardments (pin the enemy in position until their forces are prepared to attack.) This could be a good way to negate Tau counterfire (esp orbital support) and allow the Imperial forces to close.
The Fire caste are entirely committed to mobile warfare in which targets are idetnified, tracked and killed in an efficient and cautious manner. The Tau regard close combat as primitive and always plan their attacks around the application of firepower.
The "application of firepower" and "efficient and cautious" manner all sound nice, but not the "entirely committed to mobile warfare" bit. That sounds suspiciously like over-specialization to me. I'm pretty sure even modern military forces admit to a need to take/hold ground of SOME kind, especially a place to store all the stuff they need to WAGE war. A mobile force cannot exist mobile without fuel or ammo or anything like that, and supply vehicles are a finite quantity (and you can't refuel, rearm, repair, etc. when moving)? Ya gotta stop sometime.
Logistics is as importtant to fighting wars as firepower and information and mobility.
And again, this assumes the enemy apparently is iuncapable of noticing you tracking him, or detecting you back, which may or may not be the case.
Tau cities are not fortified except under the direst circumstances and, wherever possible, they attempt to either draw enemy attacks away or slow the enemy advance while an evacuation is performed. Once a city is evacuated, the Tau will defend it just as they would a region of rocky ravines, and many variants of Kauyon are solely concerned with exploiting the peculiar layout of a ctiy.
As I mentioend before, one has to wonder about resource and supply bases and supply lines, if they don't defend cities? ARe they underground or what? It has to be somewhere, ,for the reasons outlined above.
The real problem here though is that it assumes that they actually HAVE time to evacuate civilians, which the enemy may not give them. What do they do if they're caught in the midst of an evac? Those sorts of activities don't allow for complete mobility. A prime example is what happens to the Tau in Kill Team, where a dropship of Imperial Guard forces attack them from orbit without warning. If the Tau get surprised, they don't neccesearily have time (or space to trade for time) to allow them to do what they want. And as mentioned, what if they faced Tyranids or Orks? I doubt they'd play nicely either, and conditions aren't always as ideal as the situation above seems to require.
And even then if you do evactuate you just give the enemy the ability to demolish all your hard work. One must think the tau are foolish to consider economic or industrial costs in abandoning a city. That city must always be rebuilt, which takes time, money, and resources from other things. And where do those evacuated people sleep and seek shelter? How do they feed themselves? Or provide a living? This is another thing Imperial Guard artillery is good at, after all.
Again, there seem to be things tau doctrine utterly fail to address.
On the rare occasions when the Tau are absolutely compelled ot defend a vital resource, they still apply their traditional techniques. In this case, the Mont'ka is applied as lightning fast forays out of the defences, each aimed at killing the enemy that pose the greatest threat. The Kauyon is represented by feigned retreat from the perimeter to draw the attacker into a well-prepared kill zone.
Again, this is fine.. but what do they call a "vital resource?" They already admitted they won't defend cities unless they have to. Do their supply lines and resourcee bases count? Factories? Defending a static location always means trading off a measure of mobility - something the Imperium understands. For the most part what is described above does not sound vastly different from what the Imperium might do - attack mobilely from a fortified location (Key examples: Jouran Dragoons from STorm of Iron, Narmenians defending Vervunhive in Necropolis, the Armageddon Steel Legions, etc.)