A/N - I don't own War of the Worlds.
The Martians had known for many millennia that their world was dying.
They were a highly advanced civilisation; they had solved mysteries of science over the centuries, and it didn't take them long to work out their world was dying. The Martians decided to enhance their race in order to solve the problem, believing that a more intelligent species would While they had been evolving through a mixture of natural evolution and through the use of genetic manipulation with an emphasis on enhancing their already natural intellects, their dying planet gave them the motivation to really experiment into different possibilities of surviving.
The ancient Martians would never have recognised their descendants.
The Martians which would later attack Earth had become more and more of a giant brain with tentacles to give them the power to grasp and move and manipulate objects, removing more and more unnecessary material in order to increase the brain mass. The Martians considered it to be a great compromise. Sadly it also affected their morals, the genetic engineering over the generations slashed off chunks of their morality so the latter Martians would contemplate doing things for the name of their race's survival that their forebears would have never entertained. Conquest was one of them.
Sadly, while the cause was to ensure the survival of their species, not every Martian was clear about the best ways to proceed. None of them questioned their choice for survival. In the end, a faction began making plans to shoot capsules into space, carrying the DNA of their race, where they would hopefully land on a planet, with their knowledge of their history imprinted into their genetic makeup while they carried enough technology to rebuild some semblance of their civilisation somewhere in the black unknown of the galaxy.
Another faction, building up on the idea inspired by the spreading of their genetic code like flower seeds, spreading through the air in order to reproduce, strained the already dwindling resources of the dying Mars and began constructing a small spacefleet. Powered with a combination of gravitational/ion/fusion and fission engines, the fleet would go off into space, spreading their DNA as they went in much the same way as the other faction so if anything went wrong - a strange gravitational anomaly, a solar flare, or some other hazard, then their race would be guaranteed a chance of survival.
Many Martians applauded the plan, praising the ingenuity and the sheer drive, but there was a problem. The Martian ships were few in number, meaning only a small fraction of the greater populace could leave.
The lack of morality in the Martian species was not just aimed against other life forms, whom they judged as inferior to their own race, but it also appeared to be aimed at themselves. There was a brief civil war on the planet, and many Martians were killed in the running firefight for the ships to escape. Two of the ships were destroyed, their precious ships destroyed, but the others managed to escape before any more were destroyed and blasted out of the Martian atmosphere, out into space. Once this group of Martians had escaped their planet and the civil war, they began putting themselves into suspended animation, although their considerable brains were interfaced into the virtual reality universe in order to keep themselves stimulated but also aware if something went wrong with their ships, the Martians left Mars. They were never seen or heard of again.
But now… now Mars's situation was dire. The civil war had not helped the situation with so many resources more depleted and gone, and they were still trying to find new ways of survival. The spaceships had strained the Martian's capacity for constructing spaceships, so the Martians couldn't construct anything elaborate again to waste their resources. Still, the destruction of the two ships and the waste of so many of their resources forced the remaining Martians of the dying red planet to begin looking for alternatives while they began keeping an eye on their complete stock of resources and giving them limits of what they could now do.
The Martians, keeping these limitations in mind, realised that there was only one choice left open to them; they had to find a world in their home solar system, one that was perfect for them, and migrate there.
Sadly, they were strapped for choice.
They couldn't go to Venus, although the tragic thing was there had been potential for them to colonise the planet by using specialised airship colonies in order to avoid the high pressures and temperatures which would have destroyed any conventional colonisation venture. If they had looked into it before the second faction left Mars, then they might have been able to do it.
Mercury was simply too hot.
They couldn't go to Neptune or Pluto. The outermost worlds of the solar system, the planet originally had some promise with its internal heating and the moons in orbit which would have provided the Martians with a great many resources to spare, but the terrific storms on the planet would have made it harder for them to colonise the planet. In contrast, the Martians believed its neighbour, Pluto was a possibility. Although both were further from the sun, the atmosphere of Pluto consists primarily of nitrogen but also contained methane as well. And its neighbour Charon boasted the potential for life, and while the atmospheres on both bodies were far from perfect, the Martians were convinced they could colonise the two neighbours and tap into the distant Oort Cloud for resources.
Sadly reality kicked in.
The Martians lacked the resources to construct a fully-fledged fleet of ships to round the gas giants that were in between, and the original faction to leave had mined the mineral ores from the asteroids near Mars but their limited protection from radiation had only limited what they could take; now the Martians simply could not protect themselves. Pluto and Charon were off-limits.
Jupiter and Saturn were both attractive, but they were gas giants and there was no way they could ever colonise them. The Martians looked into colonising one of the moons, like Europa, but again the radiation levels put paid to those plans.
Finally, the Martians turned to their closest neighbour. Earth. They considered Earth to be perfect. Like their planet in ancient times, Earth possessed a cloudy atmosphere that was fully fertile and bright with the blue of the water visible from space. With their limited resources, the Martians concluded it was better to try to colonise Earth when their planets were perfectly aligned in orbit with each other. As they studied the planet, they watched humanity as they fought each other, growing stronger as they did, although they had a great deal more to learn before they became a threat.
The Martians saw the only impediment to their plans of colonising Earth when they realised Earth was the only way their race could survive and the decision was made to invade the planet. War machines contained within cylinders, which would be fired towards Earth using gravity pulses would begin weakening the human race while carrying the rest of their species to begin colonising the planet.
Mars would be reborn.