Taking over a planet; tips.


I'm new to this forum (still don't even have an avatar), and my reason for coming, other than my love for science fiction, is that I would like to request help from you in the form of opinions on a small mater I have long been pondering about.

Imagine the following hypothetical (or not...) situation: aliens attack the Earth. Yep, the same ol' story. The fact is that taking over a planet is somewhat difficult, and there are good ways and better ways to do it. Also, if it is to have any kind of interest, it must surely develop into something interesting it would have to be a story more than a page long, so I've thought about excuses so the aliens would not bomb the planet from orbit and end it all in seconds.

The idea would be that an all out assault would include landing of troops and assault of military or otherwise relevant structures, as well as indiscriminate orbital bombing. As a counter, the alien ships would be attacked with nuclear weapons, also harmful towards anything that lives. And (finally) my question would be: how much of the world's population do you think would remain after such a war? That is, of course, imagining we won.

I was taking into consideration the hostile conditions the planet would be left in, implying many more deaths derived from pollution, lack of food and drinkable water, and other harsh conditions. People not reached by war might be reached by the effects of the lack of supplies (as people do not remain in their working places when they are being bombed).

Thinking on all that I estimated the remaining population to be a 15%, and setting this on a near future, earth's population could be of, leaving us with some lucky This population would be distributed between the (limited) space stations, the (newly created) fleet and some well protected cities. I thought it might be too much, so I reduced this to a 10%, being it 1 out of every 10 would survive, and being this 700.000.000, a smaller number, but close to the last one (well, relatively close, since the diference is the US's population).

Anyhow, after this long post what I ask is, do you agree with these numbers, do you think it would be different? If so...how? And while we're at it, what tactics would you use to take over a planet? The reasons would be mostly resources and such, so there would be no real need to spare humans, but indiscriminate bombing of everything would not be allowed (even for aliens, bombs are expensive).

Many thanks to all of you in advance!

A scorched Earth policy or use of nuclear weapons would be a last resort. You'd need to make sure you took out a sizeable chunk of the enemy. You'd need to know they wouldn't retaliate by splitting the planet apart. Also you don't know if reinforcements would turn up, or if as prisoners, they wouldn't commit wholesale genocide.

Bearing in mind we are in a sparsely populated area of the galaxy, travel here would be prohibitive. Would an alien race turn up here in force? Would they have the shipping, troops and supplies to reach here and get back (if they failed in their attempt)?

What is their intentions? To blow us off the face of the planet, have fun torturing us?

The likelihood is a smaller force would arrive, attempt to infiltrate (if looking like us) or control the leaders, businessmen and other personages to subtly create conditions on this planet ripe for military or economic takeover, with minimal loss of life. This would give the aliens the most power/resources.

However, if we look at war where we use nukes against the enemy in desperation:

Initial weapons, standard nukes, 5 mile blast radius, 20 mile radiation deaths. Most weapons would be used on population centres where aliens land hoping we don't attack them with area effect weapons. Rest of population of planet poisoned by large number of weapons putting fallout in the atmosphere, being carried by winds and landing on people, land, property all round the world. There aren't enough people and fullers earth/chemicals to wash down the entire planet and then store the fallout safely.

Large scale nuclear war or fighting means cessation of industrial services. This means no electricity, no gas, no running water. People will be drinking contaminated drinking water. The longer this goes on, the more chance of drinking from streams that have pollution sources upstream. All water would be radioactive anyhow, even rain water. Food would stop growing properly in the ground with lack of fertilisers, poisoned earth, no seed sources.

Riots would start in the cities where people are starving, the governments would put them down violently. Crime would increase, people would be killing each other. Pets would disappear off the streets and onto people tables.

A race that has superior air power would stop vehicles and aircraft moving, the transport of food, water, medical supplies would stop.

Diseases would run rampant in cities, towns and villages. Cholera, Tuberculosis, cancers from radiation. Starvation, dehydration and disease would wipe out whole communities. Some communities have 25% disabled population, physical and mental. A lot of those would die for lack of care. Suicides would increase dramatically across whole population

Technically, only those living far away from cities in the countryside would survive longer. But the governments would attempt to drive out and grab their resources to supply essential personnel such as government and military. However, the country dwellers would potentially see less radiation and would know supplies of food and water from fields and wells.

Initial deaths from serious nuclear war? 40%
deaths from fallout within 5-14 days? 60-70%
deaths from starvation, dehydration, disease, rioting, crime within a month 80-90%
Total population left 10% and dropping.
Within first year after event? maybe only 5% of population left and no way of recovering civilisation. Genetic damage from radiation, birth count low, people dying in their late 20's, early 30's. Extinction level incident.

The choice for us to use nukes would be silly therefore. Capitulation would be a better method. Live to fight another day. Any alien force hammering away at us would need to come down to the planet before we could use nukes. Anything in orbit, moon bases, etc would have been brushed aside by the incoming forces. The aliens would have to know where all our nukes were and hammer them from orbit to stop us using them. Dropping rocks on the planet would be silly. Drop in the ocean, and we see tsunamis wiping out large tracts of coastal areas and populations of entire low lying countries. Land strikes would potentially put dust up in the air, blocking out the sun, stopping crops growing for decades.

Like I said at first, subversion by political or economic takeover is preferable. An invading force does not want to see the mineral resources of a planet contaminated. It makes the whole expenditure of attacking a planet futile. The attacking race would have to be insane to commit to a war that had no gains except satisfaction of genocide or a training exercise for bored leaders/troops.
Wow, that was an amazing reply. You took everything into consideration, and I'm very grateful for it.
The thing is I'm writing a story (a book of some sort, for the fun of it) and the idea is that aliens try to wipe us out. The story does not really follow the initial invasion, but rather focuses on some guys who go back in time to stop the invasion in the first place (kind of like terminator but with aliens). So the war that took place is sometimes recalled by the time-travellers, as in small bits of information.

I did however set some terms to that invasion, which are the ones you say would be taken into consideration as to choose one tactic or another when attacking the planet. The idea is that the aliens have better technology, but are far outnumbered, so indeed, as you said, they take their time studying humans (and their weapons) and infiltrated the world's most powerful nations armies, media and governament, intending to disrupt all kinds of possible defense and retaliation.

Even tough they dispatch a (relatively) small force, they set up a portal that permits them to jump back and forth from their nearest military outpost, so supplies are no problem, as are not reinforcements and the chance to retreat given they failed their mission (at least until the portal is destroyed).

The nuclear weapons would be fired on the enemy ships when these are as far away as possible from any inhabited place, but also when the enemy was attacking some other country, if such place was considered lost anyway (altough the country in question should not have nuclear weapons itself, or it could decide to attack whoever nuked it).

So considering that, whole countries might be wiped out by others in attemps to take out part of the enemy fleet, but there would be other countries (basically the ones with the nukes) who would not suffer nuclear bombardment, so I guess on those places people would have a slightly higher chance of surviving. That's why I tought about the 10-15%, they would represent population from countries not heavily irradiated or relatively harmless (to the alien force). Also remote places might not be reached by contamination, and people would be relocated there after the attacks ceased, to rebuild civilisation. That is given that they managed to survive the alien assault (which they do, if not I'd have no story to tell).
So while some places would suffer the consequences of radiation and all it's population would die, I guess others would be left relatively habitable, and would end up with about that 10% you said (initially I tought it might be too low, but given your points, clearly it is an apropriate number).

What I didn't really think about is the efects of orbital bombardment of a city, I mean, the central zone would be completely evaporated, but the outer zone would be left in runis, and the dust and smoke would make excelent cover for survivors to play guerrilla warfare while defending their positions, making it dificult (yet necessary) for the ground troops to engage them, so it might not be a great idea to simply hit a city from space and consider it destroyed. I will take that into account.

So, really, thanks for everything, this has been really helpful :D
I think the simplest ideas that are based on current fears and exploitable situations are probably the best ideas for readable stories. Either what we have now or what is envisioned to be viable in the immediate future. You probably have to make the reader believe they could be one of those survivors, but only by pure luck, so they appreciate why and how huge tracts of humanity get obliterated. Blame is useful too, exploiting peoples fears. The pettiness of people turning on each other even in hard situations is maybe realistic to display lowering social reasoning, a dog eat dog world so to speak. It's the old utopia/distopia vision and we're looking like heading for the second in current times as it is.