Disclaimer: Don't own anything
Note: Mostly inspired by a conversation I was having a friend the other day about how lasguns were usually fairly ineffective against most foes. We agreed it wasn't because lasguns were bad weapons, which they're not, but because everything is WH40k is just ridiculously hardcore. Also partially inspired because nobody had done a Galactica/Warhammer crossover yet.
The Imperium of Man wages a thousand wars each day. All over the galaxy, human worlds are always being threatened by xenos, spawn of the Warp or from inside insurgences of heretics and rebels. Possibly all three at the same time. Worlds were lost all the time. But the arm of the Imperium, while slow, is long and powerful, and does not take trespass lightly.
Agra Secundus was a simple farming world, one of the many that fed the more civilised worlds of the Imperium what they needed to survive each day. It was unimportant and its orbital defences reflected that. They were meagre and weak.
It was this that allowed the invaders to succeed.
The single defence satellite had picked up a squadron of small fighters jumping into the system. It was strange. No warp travel had been detected. They'd just…appeared. The broadcast was made, warning them to identify themselves as Imperial or be destroyed.
The satellite was about to open fire when the fighters winked out of existence once more.
Soon after, a larger ship made an appearance. By larger, it is meant that it was larger than the fighters. It was barely the size of an Escort-class vessel. The same broadcast was made. This time, despite making no answer, the starfish ship began to move closer to Secundus.
The satellite's single gun battery opened fire, spitting out several volley of ruby-red bolts moving at close to light-speed. The ship had less than a second to react before the first shots impacted, scissoring off large sections of the hull before carving the ship in two. It exploded soon after.
After that, three more ships of the same variety appeared, possibly looking for the previous one. They quickly met the same fate as they were blasted into smithereens. The inhabitants noticed something odd. Aside from the fact they had no shields, none of the ships had opened fire. Why not?
This question was answered later when four more ships jumped in at extreme close range to the satellite before opening fire. It was simple. The ships simply couldn't fire long range for some reason. It was as if they had no energy weapons at all.
Their weapons, slow-moving torpedoes were shot down before they reached the satellite. The gun battery then swivelled to blast all of the xenos ships out of the sky.
And so it continued, the single derelict satellite, with its single gun battery and faulty shields, held out against a veritable armada of such ships. Over and over they jumped in to attack before being wiped out.
Eventually the satellite was destroyed when a ship jumped in right next to it and rammed it, folding it's flickering void shields and wiping it out in a blaze of mutually assured destruction.
The invasion of Agra Secundus began. The ships massed over the planet, sending down wave after wave of ships to pacify the small human population. And this is how it was for several months.
Eventually, a small Imperial battle group was alerted to the situation on the planet. Not because the invasion had any great importance. But because the ships were going that way anyway so they might as well stop for a bit to clean it up.
Private Gartz's face was lit up from the red light of lasfire as he sprayed his lasgun into the enemy encampent.
He and a regiment of the Verhoven 468th had arrived with the ships to clean out any ground infestations of the xenos. And there were a lot of them. The xenos had sure been busy!
A few bursts of machine gun fire answered him, woefully off target. The xenos were using primitive slug-throwers, which had a range far inferior to their lasguns. He curled his lip in disgust as what seemed to be a human was mown down, severed in half.
They weren't real humans though. The true xenos, the metal men, had grown them somehow. It was disgusting. Not only did the xenos dare to set foot on a human planet, they went even further by daring to despoil the sacred human form.
Their blasphemy knew no bounds.
Fortunately, Gartz thought as he blew a large hole in one of the metal things, they died easily. Real easily.
He turned to Private Constantin beside him.
"When was the last time we actually fought something which died when you shot it with a laser?"
He thought back. Before this, they had helped in cleansing a Tyranid infestation, before that, a small force of Traitor Marines, before that, a fledgling waagh of Orks, before that…
"Actually, I don't think we ever have before now."
Constantin nodded as he blew the head off another Centurion.