When the Ark was built, along with the array of Installations known as "Halos", during the Forerunner's conflict with the Flood, they left behind several portals... One of them, the greatest, was built on Earth... This portal, known only as "the Artifact", lead to the Ark, the most powerful weapon in the Forerunner's most dangerous and desperate arsenal.
The Battle of Voi in 2552, would uncover these ancient secrets. But, even then, the combatants of that battle were not the first humans or Sangheili to gaze upon its magnificence and wonder. There were humans who saw it thousands of years ago, even during the age where it was being built... but one event... had more significance, as it consisted of more than gazing. It was actually quite recent that this event happened before the Battle of Voi, about six hundred years to be more precise.
A horrific war was raging on Earth; one demonstrating a symbol of the battle between good and evil... and at many points during the war, the edge was given to the side of evil... this was especially true with the events concerning the Artifact on Earth during that war...
It was the Nazis who had uncovered these secrets in 1935. The Fuhrer, Adolf Hitler, had assigned a special research division of the elite SS under the command of Doctor Hans Von Kliefen to further research into these Forerunner artifacts, after the discovery of Forerunner remains in Africa, ultimately uncovering the weapons of the Forerunners and how they work. As the war dragged on against the Fuhrer's favor, he demanded Kliefen to use these weapons against his enemies... despite the consequences... desperation made the Nazis into a very dangerous enemy, and their desperation and utter madness would have brought the end of the world, and even all life in the galaxy, in late 1944... if not for the actions of soldiers fighting for Hitler's greatest enemy...