Author's Notes: This is something I thought of doing after seeing the movie. I was exiting the theater and thinking. ''The Na'vi thought the RDA was brutal? I wonder how they would react to the Imperium!'' and so this fic was born.

The actual warfare won't take place until chapter two, I'm introducing the humans first before the battles begin.

Invasion of Pandora

Chapter 1: Arrival

Airspace above Base 16

Inquisitor Marber looked out of the window the Aquila shuttle. The smoke shrouded structure of forward Base 16 rose from the blue-green jungle below like a grey rock in an alien ocean. The pilot voxed in confirmation to Base 16's operators for a moment. After a brief vox-burst the base's comn operators confirmed the flight patterns of the vehicle and gave permission.

The Lander swooped down and jets of heat washed down as operators wearing rebreathers and carrying glow-flags directed the Inquisitorial shuttle down to a large empty landing pad painted with faded yellow markings. The shuttle landed lightly with a thud and Marber got up from his seat. He pulled on his breathmask. Karlon, his savant, followed out from behind him as Marber got up and gave himself one last weapons check.

''As a reminder sir, this atmosphere is highly toxic, are you sure your rebreather is on fine?'' Karlon asked, his voice transmitted through a throat-mounted vox unit. Marber's savant was heavily modified with augmetic lungs. Rebreathers were unneeded for him.

Karlon was a withered, pale, shell of a man. He was swathed in thick brown robes with the golden 'I' symbol in front. His lower half was an automated set of four spider legs that clacked on the metal floor of the landing bay. His forearms where replaced with metallic access and datathief instruments. Karlon was a gift from his master. Inquisitor Lord Gedsar. Marber had served with the hoary old veteran for eighteen years as one of his acolytes. Finally, after much time, he had been promoted to an Inquisitor two years ago. He had entered the Ordo Xenos, as had his master, a practice common among Inquisitors.

And know he was here on Pandora.

Or more accurately ZL-106, as was it's official designation, but somebody in the top Guard brass had gotten into the habit of calling it Pandora after some old Terran legend. It stuck.

''So this is the place'' he muttered to himself. Marber stood at average Imperial height, clad in a field uniform of syth-cloth and grox leather. He wore a segmented Tarsian carapace suit over his torso and limbs. A saber and a bulky looking bolt pistol where holstered on is belt along with other shapes.

He and Karlon walked quickly across the broad, concrete fields, Guardsmen flocked around the place like worker insects at some hive. Some hauled around boxes of ammo or other pieces of equipment, others were taking apart a husk of a broken Chimera, or some other mundane task.

It was nothing he really cared about, he already had an objective.

''Catachan, Thirty-Sixth regiment, commanded by Colonel Landers, total strength two thousand three hundred and thirty six Guardsmen'' Karlon began.

''I already read the reports, I'm familiar enough with the Guard here'' Marber replied. The troopers were all lean muscular types, wearing light flak jackets and sleeveless shirts. All wore some form of blue-green camouflage. All wore rebreathers.

Pandora'a atmosphere was highly toxic to humans. If one breathed it in without any kind of filter or augmetics they would be paralyzed in forty seconds and dead within four minutes. Pandora was like a beautiful, but poisonous flower. Marber had been briefed somewhat on what the Imperium knew about the local fauna and wildlife, but he had been forced to admire it's intoxicating beauty as he came in from orbit.

The Imperium had had full operational bases here for a mere five months, and Guard forces had been here for a mere two years. Even now the Genetors of the Mechanicus were still trying to unlock the secrets of the deadly Pandoran wildlife. The Guardsmen however learned only the rules of survival on this planet. Due to the nature of the terrain the Catachan regiments where a natural choice for the planet, but they were not the sole type of soldiers sent.

Cadians, Vardian, soldiers from Luther McIntryne where also sent here among various others. So far none had adapted well as the Catachans, who took the dangers of Pandora as a challenge. The fauna here was deathworld class easily, the predators here where many varied and all deadly. But of all the dangers of Pandora the local xenos breed had been the most deadly.

The ''Na'vi'' as they where called, were tall blue humanoids that apparently took offense to the Mechanicus teams that landed on the planet in search of raw materials. The tech-priests began the extermination of the xenos, but it was soon revealed that the Na'vi were far more numerous and dangers as first thought.

So the Guard got called in.

All for unobtanium, Marber mused. The Imperium would not be here if not for that metal. Unobtanium was one of the most rarest metals. It's primary use was as a super conductor for plasma and fusion reactors. In other words it was vital for use in rare technologies like Starship drives, plasma reactors and weaponry, and void shields. All items that the Imperium increasingly was starting to lose.

Very few planets that the Imperium had found possessed unobtanium and very few of them in turn could be found. Pandora was a lucky find, and the Mechanicus descended upon it. The planet was rich in unobtanium, with 93% of it concentrated in the jungles. Their efforts at strip mining so far had failed because of the death world class environment and the natives.

Various Imperial tacticians and xenobiologists had theorized that the Na'vi themselves where using the jungle itself to fight. Autopsies had revealed that the xenos possessed and ability to link themselves to the various wildlife. Because of this the Guard had been sent in to clear out the Na'vi and destroy as much as the jungle as possible. Despite being outnumbered fifty to one the vastly superior technology enabled the Imperials to make gains.

Of course, the unobtanium was a mere side objective, Marber came here for a different reason, one that was vital to the Imperial conquest of the planet and the Inquisition's own secret agenda.

He came to an entrance gate. He flashed the Inquisitorial rosette. The two Guardsmen looked at it briefly and then pressed the button, Marber and Karlon entered in the room. The doors slammed shut behind them as the air filtered recycled the outside air with a hiss. A nearby rune-marked panel glowed red for several moments before switching to a bright green.

Marber removed his mask and took a long breath. He had narrow, gaunt features, with hangdog eyes. He cracked his neck from side to side, trying to work out the kinks. He swept his close-cropped black hair back as the doors in front opened. He and Karlon exited among the hallways. Various Guardsmen moved about, along with servitors and various Munitorum adepts. He grabbed the shoulder of a red-robed adept.

''Were is the Colonel?'' he asked pointedly. The adept was startled.

''Who are you-'' he began, but Marber cut him off.

''Inquisitor Stark Marber, Ordo Xeno, I've got urgent business.'' he said. He did not really have any time to waste. He did not bother to threaten the adept. A simply request sufficed.

''He's in a command meeting, three hallways down on the right. I don't think he should be interrupted.'' the adept replied, somewhat shaken, which was normal, considering the reputation of the Inquisition.

''He's already got notice that I'm coming.'' Marber answered, letting go. He turned to Karlon

''Let's go.''

Captain Loal Torenson walked in, dog-tags jingling as he looked around the command room. It was a large room, about thirty meters long, and lined with various monitor screens that controlled Base 16's systems. Servitors were plugged into each station. At the end, on a high pedestal dominated by a huge, holo-screen was Colonel Landers and the rest of the 36th's officer cadre. All gathered around the raised holo-scree. He checked his wristwatch. Good, he was the last one here.

Torenson knew this was going to be another hell-mission. He had not been on actual tours for almost a week now. Standard Imperial time. He had a sense the colonel was saving him up for something. A week of spending time on the firing range and running Base 16's small exercise course did little to relieve his boredom. Nether did burying himself in his own dog-eared copy of the Tactica Imperium, Volume XX.

Flights into Base 16 had been slow these days and Volume XXI had not arrived yet for his pleasure. Torenson was considered a bit of a bookworm among the Catachans, he was considered rather unconventional for his hobbies. Back on Catachan there had not been much time for books. It was a constant struggle for survival, you learned Imperial Basic and then devoted all your time to survival tactics and the lasgun. Once Torenson had been chosen from the PDF to join the Guard tithe he had found reading various tactical manuals a great way to spend the time on long trips in space.

A row of toughened faces greeted him. Colonel Landers, the old man, looked down as he raised one flint grey eyebrow. He was fifty, ancient for a Catachan guardsmen considering the line of work they did. Despite his age Landers was made of steel, almost literally, part of his chest was replaced by augmetic lungs almost nine years ago after an ambush by the Eldar on Rorsa Prime. Unlike most people in his regiment Landers could breathe the Pandoran air freely. He was fitter than men half his age.

His signature power fist was not present instead he had only a holstered hellpistol. Torenson had brought along his chainsword and bolt pistol himself, and many of the others where armed.

There was huffing as a tech-priest tinkering around in one of the lower hatches. Blue light flickered up from the pedestal and formed a map of the local terrain. Area 16, thirty miles of terrain that the 35th was expected to patrol.

''Alright, let's get this over with ladies and gentleman'' Landers said. He pointed one finger out. ''We've finally gotten a good idea how to clear out this area, I know, sounds too good to be true, right?'' he asked.

It did sound too good to be true. While the Imperial Guard slaughtered the Na'vi in open warfare, the results where different in guerilla warfare. The dammed blue xenos quickly began to use hit and run attacks.

The huge amount of electromagnetic made communications patchy at the best of times and the magnetic interference and flocks of flying creatures made high-level aerial support hard to do. Valkyries helped in transportation and assaults, but there was never enough of them. Chimera and Hellhounds were the order of the day, along with foot patrols by the guardsmen themselves.

The Catachans excelled in such terrain, Catachan itself being far tougher than this little blue-green rock, Torenson thought. However the natives had the home field advantage here.

''A surefire way to success? What is this crap?'' asked Major Tosaka, the second in command of the regiment.. ''This something from command?'' he asked.

''No, it's from the Inquisition.'' A new voice said. Torenson's attention was turned to a man coming out from a group of Munitorum adepts, how he had made himself unnoticed to then, Torenson did not know.

''This is Inquisitor Marber, of the Ordo Xenos,'' Landers explained. ''He here to help us deal with our bluie problem.'' the Inquisitor quickly took up position.

Torenson was apprehensive as any sane man would be when thinking of the Inquisition, he was also suspicious. Catachans did not trust anyone that came off-world, they were too independent minded. The air in the room seemed to shift into something more apprehensive. The Inquisition was here, and that meant something had gotten more than just a normal bushfire war.

Torenson eyed the Catachan colonel

''Correct,'' the Inquisitor tapped something and pulled up the holo-screen, he pointed out a six mile section of the jungle. ''You already know the current tactical situation, so I won't insult you be repeating it.''

''Know you all know that the xenos are able to link up with the wildife?'' he asked. Torenson knew it well, although he did not like to think about it. The whole concept was rather disgusting ands reminded him too much of the alien Tyranids.

''That's a given, we all know tha.t'' the Major crossed his arms.

''Ever wonder how they do that?'' Marber asked. Without missing a beat he continued. ''It's because the entire planet is alive.'' he explained.

''What?'' one of the officers raised an eyebrow.

''This ecosystem is some-sort of semi-sentient xenos creature.'' he explained

Torsenson was surprised at the implications. So this was not a forest at all but some huge xenos creature of some sorts? That was decided unnerving even to the Catachan.

''The green covers this entire planet, surely it can't be that big.'' he stated. The Inquisitor looked up at him.

''It's not really a creature as we understand, but more of an interconnected jungle that directs the environment to attack, that's why you have been fighting the wildlife almost as much as the local xenosbreed.'' he explained.

''This is unbelievable.'' Totsaka sighed.

''Whether believe it or not, we are going to launch a strike against the xenos regardless.' Marber explained.

At this everyone gave him their full attention.

''This area, I believe is the location of an 'nerve center' on Pandora. This 'nerve center' is essentially a key part of the planet's coordination, it's also as important religious site for the xenos.'' Marber explained.

''We were unable to pinpoint the exact location from orbit, because of the atmospheric interference on Pandora, so I need to lead a kill team to reconnoiter this area'' Marber fumbled around on the controls.

''We need to reconnoiter the area, if we find this place and destroy it, it will significantly reduce the ability of the enemy to fight back, regardless of whatever this crap about being a nerve center or not is true there's evidence to support increased Na'vi activity in this area'' Colonel Landers explained.

''That area,'' Major Totsuka began, eyeing the place. ''That's Sector 1604, one of the most heated areas in this sector, you can't seriously be sending this man along with Catachan into the Green.''

''Oh, I have my own tricks, don't worry about me, I can hold my own.'' Marber said, with a genial smile. Torenson knew this man was holding out some sort of secret from them.

''Who is to lead this team Colonel?'' he asked, almost envying the poor sap who would do it.

''You are.''