Interface engagements

[mbrinkhues]

This raises a question: would the majority of planetary-surface invasions be conducted after total orbital superiority has been achieved by the invader, or would, in many cases, an invasion will be launched while an orbital battle is in progress in order to tip the scales in that battle (e.g. knock off SDB hideouts/fueling-posts, missile batteries and deep meson sites)? And is it possible for the orbital zone of a planet to be contested (i.e. no side having total control) for a prolonged time all while planetary forces are clashing as well?

I'd say first wave goes down halfway through the battle. With the enemies mobile space assets pinned or destroyed I can start landing troops to take out that <expletive> deep meson guns and PAD batteries. This would than result in some heavy ground battles (Think Spetznatz against NATO guards in Cold War style). If my forces fail to clear at least a landing zone, they are likely lost but that is a risk Battallion-Sized SpecForce have been taking since the days some 300 gays<<<guys took position in a valley somewhere in Greece.

Taking out those installations will allow me to use smaller units for planetary support where I otherwise would need the heavily shielded and armored battleships to brave the planetary defences. Depending on the rules set a squadron of 3000-5000dton Hull fitted with Lasers (for point defence) and missiles batteries / THOR launchers could do the job as well as a battleship but with less manpower/costs and more flexibility.

Using this strategy would also allow limited invasions to take place. Take a large Island (Say Ireland), destroy/jam the enemies sensors around and either wait for his next move or use it as a base for attacks. At that point he can:

a) Blind-Fire his remaining Meson sites at you, missing quite often and destroying his land/killing his people
b) Come out to fight and risk Ortillery fire
c) Huddle up and wait for you to come at him

Meanwhile you can build up your forces. It won't be totally safe, enemy commandos will be a massiv problem as will the occasional air/space attack.

 

[Icosahedron]

Take a large Island (Say Ireland),

Sounds easy when you say it fast - the English have been trying to do that for over 200 years!

Joke - please do not escalate into Pit territory

Just saying it might not be as easy as it sounds.

 

[mbrinkhues]

Sounds easy when you say it fast - the English have been trying to do that for over 200 years!

Joke - please do not escalate into Pit territory

Just saying it might not be as easy as it sounds.

No danger here to put it in the pit.

Surely taking any large land-mass against defences is difficult. But anything smaller is to easy a target or to quickly wrote off. I.e take the equivalent of "Helgoland" and the planetary government likely will be willing to write of the population (< 1500 IRL) as "collateral damage" to get rid of the invader.

OTOH you don't want to take a large continent since that would give you to much border to defend and to many locals to keep at bay. So a nice big island with a sizeabel but not to big population is the first choice to land an invasion force.

If the land can feed your army all the better but if given the choice between Shillelag-wielding unruly locals and resonably calm ones, take the latter even if you have to eat Ice-Shark or MRE

 

[jcrocker]

OTOH you don't want to take a large continent since that would give you to much border to defend and to many locals to keep at bay. So a nice big island with a sizeabel but not to big population is the first choice to land an invasion force.

If it's an all-grav vehicle force, you'll have the same boundry area to defend regardless, would you not? They'll just fly tanks at you over the sea.

In one of the Traveller's Digest magazines they talked about the Invasion of Terra, if I recall the three spearheads were in the Australian Outback [ok, that is an island], North African desert, and American Southwest - away from population was more important to them. It's been years since I read it, I'll have to try to find it and have another look.

 

[jcrocker]

Well, I was close.

Travellers' Digest magazine issue 13, page 51:

"The Imperial Marine occupation of Terra began on 105-1002 when the troops of the 4217th Imperial Marine Regiment raised their colors over the cratered tarmac of the La Grange Starport..."

"From their initial lodgements in Australia, North America, Europe, and South Asia, the Marines expanded their operations, serving as spearheads for Imperial offensives, and were never driven out of their "beachheads" ."

There's a map of Terra in the issue, and La Grange Starport is shown as being in the north-westerly part of Australia, a few hundred km from shore. The other two class-A Starports shown are AECO Starport in the Algeria/Tunisia/Lybia area, and the Paulo Starport [named Phoenix at the time of the invasion] in the American Southwest - I'm guessing near Phoenix, Arizona.

You'd imagine that starports would be priority targets, but I suppose on Terra there'd be plenty to go around.

 

[Icosahedron]

If it's an all-grav vehicle force, you'll have the same boundry area to defend regardless, would you not? They'll just fly tanks at you over the sea.

Or under it.
However, with an island there is a limit to what you need to occupy and what the enemy can occupy or use as counterattack bases.

In one of the Traveller's Digest magazines they talked about the Invasion of Terra, if I recall the three spearheads were in the Australian Outback [ok, that is an island], North African desert, and American Southwest - away from population was more important to them. It's been years since I read it, I'll have to try to find it and have another look.

I suppose the question of whether you use desert or population centres for your beach head depends on what you think the enemy can throw at you to repel your invasion. If they have mesons or nukes, I think deserts would be very unhealthy places to land. OTOH, if the population is likely to stab you in the back to the last man, woman or child, centres of population are going to be very dodgy places to sleep soundly in your beds.

 

[dccarles]

Transport and Insurgency

One question hasn't been addressed: if you're trying to take a High Population world (or even one with a significant population that's not hi-pop) how do you keep the civilians in line?

Assume that your transport is half passenger space, and every troopsicle takes up 2 dt (one for the trooper, one for vehicles, supplies, and other toys.) So a transport can carry about one quarter of its displacement in troops. (Your mileage will, of course, vary greatly.) How many troops does it take to occupy a world?

The US Army suggests 20 troops per 1000 civilians. So one billion people would require 20 million troops. If we have a million tons of transport available, and our base (with an unlimited amount of screaming marines) is one jump away, we can land 250,000 troops every other week. That's three years of nothing but schlepping, and we're ignoring accumulated casualties and supply requirements.

There are, fortunately, some mitigating factors. For one, the 20/1000 ratio doesn't take technology into account. High-speed grav APCs can deliver reinforcements to beleagured troops in less time than it takes for the (wheeled) fire department to arrive in our limited TL 7 experience. High-tech armour can defeat high-tech slugthrowers (though it gets expensive very quickly.) In our world, insurgents can be armed with roughly the same personal equipment as the troops; this won't hold at TL 11+.

The second is that no one said the occupying troops had to play nice. As a counterinsurgency tactic, brutality works very well, and nuclear weapons make brutality easy and fun (if you're that sort of civilization.) Zhodani can win the hearts and minds of the populace (literally.)

Still...it might be hard to get the ratio down to an acceptable 5:1000 or so. I suggest the higher the law level of the world, the easier it will be to subjugate - the insurgents will have fewer weapons available and the population will be more accustomed to taking orders.

--Devin

 

[R_Chance]

One question hasn't been addressed: if you're trying to take a High Population world (or even one with a significant population that's not hi-pop) how do you keep the civilians in line?
The US Army suggests 20 troops per 1000 civilians. So one billion people would require 20 million troops. If we have a million tons of transport available, and our base (with an unlimited amount of screaming marines) is one jump away, we can land 250,000 troops every other week. That's three years of nothing but schlepping, and we're ignoring accumulated casualties and supply requirements.
There are, fortunately, some mitigating factors. For one, the 20/1000 ratio doesn't take technology into account. High-speed grav APCs can deliver reinforcements to beleagured troops in less time than it takes for the (wheeled) fire department to arrive in our limited TL 7 experience. High-tech armour can defeat high-tech slugthrowers (though it gets expensive very quickly.) In our world, insurgents can be armed with roughly the same personal equipment as the troops; this won't hold at TL 11+.
The second is that no one said the occupying troops had to play nice. As a counterinsurgency tactic, brutality works very well, and nuclear weapons make brutality easy and fun (if you're that sort of civilization.) Zhodani can win the hearts and minds of the populace (literally.)
Still...it might be hard to get the ratio down to an acceptable 5:1000 or so. I suggest the higher the law level of the world, the easier it will be to subjugate - the insurgents will have fewer weapons available and the population will be more accustomed to taking orders.

--Devin

Well, I suspect the Imperium has better surveillance than the US Army, faster response times and firepower that is more than just overwhelming. As you've mentioned... you seem to have answered a lot of your own questions. Even if your not into scorched earth, brutal demonstrations of power, or mass murder, high pop / urban planets are also vulnerable to control in ways that low pop ag backwaters are not (i.e. food and transport, energy supplies, etc.). If an area is restive -- cut it off from power, fuel, food, etc. and see how long it stays that way. Then too, just how much of the local population do you really need to control? The starports and the areas around them. Unless your planning on a permanent stay not much else. And if you are, you have the time, the means, and presumably the will, to manage the job.

 

[dccarles]

Well, I suspect the Imperium has better surveillance than the US Army, faster response times and firepower that is more than just overwhelming. As you've mentioned... you seem to have answered a lot of your own questions.

Not entirely: I was implicitly inviting debate about how easy or difficult an occupation may be. Every world is, of course, different: your jump performance will vary greatly. IMHO, the official vehicle designs (Trepidia, Astrin, etc.) are too slow (fast as they are) to be really effective as quick-response vehicles.

One consequence will be that there are two entirely different strains of fighting force: a force designed to take worlds, and another for world defense. (Occupation is a separate task entirely.) Which fits nicely with the division between Marines and Army.

The Imperium's major problem is that, with all their technology, they still can't figure out who the insurgents are. (Zhodani, of course, are better equipped in this regard, but with the danger of really pissing off a psionics-paranoid population.) Which leads me to believe that the technological reduction of necessary troop ratio wouldn't be as great as one might hope.

--Devin

(Come visit scenic Ilelish! Extra-low rates for equatorial tours!)

 

[Renaissance Man]

One question hasn't been addressed: if you're trying to take a High Population world (or even one with a significant population that's not hi-pop) how do you keep the civilians in line?

A lot of these issues were brought up in another thread.

One of the initial assumptions was: if a dirtside engagement often occurs after a successful space engagement, invaders will have a massive advantage thanks to ortillery. That means that defenders will resort to, and be prepared for guerrilla warfare as a matter of course. And the Imperial Army will be geared towards those types of conflicts.

Of course, after talking to the brain trust here, I realized that things are usually a lot less cut and dried than that. Though I think most agreed that protracted guerrilla conflicts would be a common feature in 3I warfare as ortillery-backed invaders try to hold restive captive populations.

This and other threads along these lines beg for some way to organize our vision of high TL.

From my point of view, there are certain features that stand out

1) Specialized atmospheric craft have little utility for world defence, since they are vulnerable to ortillery while active, and their speed cannot help them. They are useful in troop transport for the invasion force, where high NOE speeds get troops to where they are needed faster, and aid in avoiding ground-based anti-air weapons. Battledress is also a useful insertion vehicle because of its size and comparatively low signature.

2) Passive and active camouflage are at a premium for defending forces, who must invest everything in avoiding orbital bombardment. With DS Meson installations likely being a rarity (due to cost, TL and politics,) most surface defences will be small to medium sized, and cleverly hidden. Reserve SDBs will likely find refuge under oceans or in canyons.

3) Intelligence is the principle challenge for invaders. Jump distances are long, and high TL worlds can change their defensive arrangements quickly after encountering scouts or initial hostilities. All too often, invaders will reach a system with intel that is months out of date. That means that locating positions of both ground and space-based system defences can be an ad-hoc affair. The element of surprise can be entirely worthless if you end up foundering about a system looking for targets. Whole campaigns can be built around being an advance set of military intelligence agents trying to suss out a world's defences ahead of a major invasion. You better bet that you can't just find and study a defence installation without raising flags. They will be closely guarded secrets on any world facing the risk of attack (no matter what law level.)

4) In keeping with 3, information and communications will be an abiding battlefields in themselves throughout the invasion and occupying process. Invading and defending armies will both be employing small drones, satellites and robots for the purpose of collecting battlefield intelligence and transmitting it to command and control facilities. Both sides will then also have a variety of kill vehicles for these intelligence devices. To avoid jamming, both sides will likely use a rhizomic or web-like network of line-of-sight laser and maser communications. And while invaders will have the benefit of orbit for communications purposes, defenders will have the benefit of buried trunk lines that are difficult or impossible to detect.

That's all I can pull together for the moment...

 

[whartung]

You don't need to occupy the entire world, nor necessarily a large part of it.

You need to occupy the major resource centers, and major production centers. Basically, you need to occupy the means from which a more formal offense from indigenous forces can be supplied. Those centers you can't control can "simply" be, umm, "reduced", denying them to the guerillas.

You'll "always" be limited to some kind of guerilla operations. If the population is 100% hostile, there is little you can do but punish the population (or leave), which doesn't help your goal.

In time the population becomes the occupying force, not your own forces. This is implicit to the invasion, it's simply the reality that the local population needs to be co-opted in some way to facilitate control. It's not 100% reliable, but it's workable.

There will always be set backs, but over time policing can be improved and control more firmly established. At a generational scale, the population will eventually "like it".

Orbital combat patrols and platforms can enable quick responses, and act as deterrents. Having a "Hammer of God" handy and at your whim is a powerful tool.

Finally, it's a matter of why you are there at all. It may be necessary to "invade" the world, but, for example, merely to control its shipping facilities to deny those services to the enemies navy: construction, munitions, maintenance, and fueling. That narrows the scope to defending your positions, rather than expanding them. Different problem entirely.

 

[dccarles]

Some good points there, whartung and Renaissance Man. I'm making the assumption that yes, indeed, you do want to occupy the whole world semipermanently (temporary/partial occupations not being anywhere near as much of a problem.) Ultimately, of course, it boils down to political will.

If the attacker has the will, the defender can't win, given the number of resources even a small interstellar state (e.g., the Sword Worlds) can bring to bear on a single planet. (We are, again, considering one world in isolation. Multiple fronts provide multiple problems.) But the defender can make investing a planet very, very expensive.

One tactic I think any defending army would be wise to take advantage of is strategic fortifications. I recall a battle where the attacker had a tremendous advantage in artillery, yet didn't manage to neutralize the defending infantry, even with 16" guns. While not every army will fight to the last man as the Iwo Jima garrison did, the assault had to be out of all proportion to the sze of the island. So I suspect planetary will dig, and dig deep.

--Devin

 

[R_Chance]

One tactic I think any defending army would be wise to take advantage of is strategic fortifications. I recall a battle where the attacker had a tremendous advantage in artillery, yet didn't manage to neutralize the defending infantry, even with 16" guns. While not every army will fight to the last man as the Iwo Jima garrison did, the assault had to be out of all proportion to the sze of the island. So I suspect planetary will dig, and dig deep.

--Devin

The weaknesses of that type of defence are fairly obvious though. If there is no outside force to relieve the planet it's just a matter of time. Better to rely on a system wide defence including fixed planetary defences, SDBs, mobile (jump capable) forces etc. The whole Japanese strategy was one of attrition, to inflict the maximum casualties on the US and hope it quit. Didn't work out too well... when the casualties did get excessive the US used the A-bomb. Essentially the equivalent of a planet buster in interstellar terms. Of course given a world whose value was intrinsically high that might not be a valid tactic. In any event if you're going to do the interstellar equivalent I would suggest using the whole system not just one planet (hidden SDB bases, depots, meson sites, missile sites, mobile asteroids, etc.).

 

[jawillroy]

"(hidden SDB bases, depots, meson sites, missile sites, mobile asteroids, etc.)"

I was imagining running a game where the PCs were in control of different elements of an invasion fleet going into that kind of a situation, and suddenly, it felt a whole lot like a Dungeon Crawl. All those traps...

 

[dccarles]

Better to rely on a system wide defence including fixed planetary defences, SDBs, mobile (jump capable) forces etc.

I was assuming that, if the enemy has landed on your world, these have failed. Densitometer technology was something I was also assuming wasn't a problem; if it exists IYTU, it would make attacking a tunnel complex much easier.

I don't think the supply issue would be as much a problem as you do, though: a tunnel network can hold a massive stockpile, and at TL10+ food can be synthesized. In any case, a siege costs the attacker time.

Your point about defense in depth is well-taken, though. A system with multiple defenses to reduce will be a tough nut to crack, and take precious week. On a strategic scale an interstellar war starts to look a lot like a conventional land engagement: fast, powerful forces try to punch through the line, leaving the slower fleets to follow up and take/hold ground.

--Devin

 

[R_Chance]

I was assuming that, if the enemy has landed on your world, these have failed. Densitometer technology was something I was also assuming wasn't a problem; if it exists IYTU, it would make attacking a tunnel complex much easier.

I don't think the supply issue would be as much a problem as you do, though: a tunnel network can hold a massive stockpile, and at TL10+ food can be synthesized. In any case, a siege costs the attacker time.

Your point about defense in depth is well-taken, though. A system with multiple defenses to reduce will be a tough nut to crack, and take precious week. On a strategic scale an interstellar war starts to look a lot like a conventional land engagement: fast, powerful forces try to punch through the line, leaving the slower fleets to follow up and take/hold ground.

--Devin

I agree. As you noted, the only thing the final fall back planetary defence can buy the defender is time, and even that is limited. Additionally, if all you hold is the main system world there are typically other refueling sources available in a system and the enemy can pass forces through to their next target system.

That places the burden on the defender's mobile forces to return and rescue the defenders. On the other hand, if you can deny the attacker the use of all, or most, of the systems resources you've created a real strategic problem for him. That's why, as a fleet commander, I wouldn't invest as much resources in the final assault (assuming it had no political value, like Earth in the Solomani - Imperial conflicts) of a main world, as I would in taking the system itself. The planetary seige is just a matter of time. The system is vital to interstellar travel and naval warfare.

 

[szurkey]

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[mbrinkhues]

Few fortifications in history could survive without a mobile force from the outside coming to their relief. For a long time it was a race between the defenders starving and the attackers catching various plaques or running out of resources. See the Sieges of Vienna for classic examples of both a siege broken up by lack of food and one broken up by relief forces.

At the same time a fortress on it's own could never hold territory or keep heavily armored enemies from bypassing them. Their value was that of a force in being They could be defended by a small garrison and took a large enemy force to take. So if the enemy decides to take a fortress he will wast large numbers of soldiers. If OTOH he bypasses the fortress, small raiding groups can sally force to attack the rear areas, food transports and/or gathering parties etc. The Maginot Line is an example. The Germans would have been able to push tanks through the gap between two grand ouvrages but the fuel trucks and troop transports would have been unabel to follow(1) And with the mobile forces originally stationed there the tanks would have been sitting ducks relatively soon.

The function of defences in Traveller is similar. Between the heavily shielded defences of the planetary bodies and the mobile (SDB) forces a well-defended system gives the attacker the problem of either cleaning the system or keeping a potential danger in his rear. Assuming a high enough TL the main world will be able to repair and even build fighters and SBD forcing the enemy to picket the system with enough strength to keep them bottled up if he wants to use the system as a transit point. This might get even worse if the system can build Jumpships, supporting and even building raiders. After all they have the resources of a whole planet at their command.




(1) IRL they used the undefended gap between the Maginot/South and Maginot/North in the Ardennes after the breach of the Belgian lines had caused the shift in French forces to that border. The one case where they tried to punch through the northern lines ended with a small fort taken and the germans still unable to use the breach. Same for the Italiens in the south.

 

[Renaissance Man]

In Traveller, why would you invade any world if you don't have to? If the needs of the fleet can be met without invading, keep moving forward and don't waste time, lives, or MCr invading and garrisoning. Use orbital bombardment and/or areospace attack to shatter their war-making industry and move on. As for SDB, if they are so effective at hiding, why not just deploy your own to hunt them down playing the same game.

Okay... so suppose you overrun the whole area in this fashion over a period of a few years. Besides leaving ships behind to enforce the blockade and keep the system, EVENTUALLY you're going to need to go down there and claim the planet. Two years is a long time for a ground-based resistance to get it's act together, assess the pattern and danger from orbital bombardment, and hone it's insurgency skills.

You can starve them until they surrender. But then, once you go down there, its back to square one.

Ultimately, every planetary invasion boils down to a political op. You wouldn't have launched the war in the first place if you didn't want control of the planet, it's resources, or at the very least the space lane. Through force, fraud or diplomacy, an invader must bend the population to its will.

 

[dccarles]

In Traveller, why would you invade any world if you don't have to? If the needs of the fleet can be met without invading, keep moving forward and don't waste time, lives, or MCr invading and garrisoning.

I know the question is rhetorical, of course, but it leads naturally to the question of why one does need to invade all or part of a world. I can think of a few reasons:

Political
* To aid a favoured ethnic or political minority,
* To have a Great Victory for the newstapes,
* To (ultimately) annex and assimilate the world.

Economic
* To loot,
* To exploit its resources or industry (in the medium term),
* To destroy its economic base,
* To enforce a preferred economic scheme.

Military
* To break the morale of the other side,
* To gain access to its bases and repair facilities,
* As part of a campaign to completely clear the system of hostiles.

And this is just the tip of the ice cap. I'm sure people can think of dozens more.

--Devin