The Void Engineers are one of the Conventions of the Technocracy.
Early History
There have always been men and women who sought to find out what was over the next hill. When humans were still tiny in number and confined to Africa and the Mideast, what was over the next hill may not have been seen or imagined by anyone before...and so it might as well not have existed at all. But our beliefs shape the universe, so when people sought out to explore and find what was out there...something was out there for them to discover. These early explorers were the ancestors of the Void Engineers. It was they who struck out across the Bering land bridge and first found the Americas, and it was they who guided Leif Ericsson and Christopher Columbus to find it again in a new way. They built great ships and sailed to the edge of the world, hacked their way through dense jungles, climbed lofty mountain peaks, and filled in all the blank spaces on the maps and globes with newly-discovered parts of reality.
Modern History
Once the poles had been reached and charted, the last mountain climbed, the last depths of the ocean plumbed in diving bells and submarines, and the last lost city found deep inside a jungle or out in a trackless desert, the Explorators still had work to do. So they reorgnaized themselves as the Void Engineers, and dedicated themselves to exploring the deep reaches of the Umbra. To accomplish this, they built vast magical starships known as Umbral Dreadnoughts, and flew them out among the stars while the unawakened humans were still wondering if heavier-than-air flight was even possible. It was they who discovered the canal-building Martians and the ancient civilizations on the far side of the moon. And when these alien races would not submit to the Technocracy, it was the Void Engineers who created modern astronomy and the space race, not to trade with or even subjugate these aliens, but to spread the belief that they never even existed in the first place. A few faked moon landings and Mars probes later, and humanity's collective belief that the Moon was an airless wasteland and Mars a vast and lifeless desert reshaped reality, and the alien rivals were erased from existence altogether.
Gehenna and Beyond
But the Bug landing in Rio De Janiero could not be erased from humanity's collective imagination. It was an unforeseen event, an undeniable fact, and it simply had to be dealt with. The Void Engineers brought their Umbral Dreadnoughts out of hiding, declared the Deep Umbra to be Hyperspace, and founded Earth Fleet. Exploring further than ever before into the Deep Umbra, or Hyperspace as it was now known, they sought out any other possible alien threats to humanity. And so of course they found them, in the form of the Drakat, Katarn, and especially the Horadrim. Realizing the power of the Horadrim's advanced technology, and the vulnerability of that race due both to their lack of true Magick and their incredibly depleted numbers after milennia of fighting the Caal, the Void Engineers kidnapped and took back to Earth the last of the Horadrim children. Experimenting on these children, the Void Engineers learned much, but they also brought the wrath of the Horadrim and the Bugs down upon humanity like never before. But this meant more ships needed for Earth Fleet, and more influence and prestige for the Void Engineers. When the Syndicate and the New World Order fell to squabbling among themselves for political and monetary power, the Void Engineers tried to stay out of it. But their puppets in Earth Fleet eventually helped to install Arthur Clarke as Chairman, putting an end to the conflict by crushing the Technocracy's political and economic power bases. The Void Engineers officially disbanded to avoid being crushed as well, but most of their members survived the purges and are still busily working away, designing Star Control Ships and plotting the galaxy on their starcharts. After all, what are petty human poilitics when you have an entire universe to explore?