The Advent War
The Advent War, otherwise known as the Contact War, was the war between Aempis and Earth which resulted in Earth becoming a protectorate of Aempis.
In the war between God and Euphraesthi, God was a no-show.
A Violent Spark
Friction between humanity and Aempis was nearly instant. Earth, rich in quartz, was a prime target for Aempian mining, and could prove the decisive element in their ongoing conflicts against Valuserr'h. This, combined with religious tension on both sides and the purposeful exacerbation and escalation of conflict by clandestine Valuser'ran operations lead to open war.
At first, the Aempians fared badly on earth. With no home field advantage, they lost by land, sea, and air. The Aempian emperor Akotan, who was now under attack by Valurser'rh, had no choice but to push the war regardless, and sent in battle troupes of Psiolic and Divinoriums.
Where the Sazashi forces had quailed against human technology, humans quailed against metaphysics. The Aempians turned every battlefield against humanity and forced their own homefield advantage.
The war became one of attrition for both of them. Years of bloodshed followed, with both sides taking heavy casualties.
The Fall of Mars
Humanity. I have found among you a sentiment: "An Eye for an Eye makes the whole world blind."
I assure you that for every Sazashi eye you gauge out, a thousand more will open to look upon you, until all the stars of the night sky are but the whites of our army descending upon your world.
In a desperate bid to finally end the War, Aempis mobilized a weapon it had been working on: Torkh Sajhu Veath—Our Lady's Scorn. Protected by a fleet, it flew for the densely populated cities of Mars. Many ships were lost in bombardment, but Akotan himself manned and protected the Veath with his power, and pressed the button which fired the weapon and destroyed the capital of Mars.
Coming to terms
Humanity, realizing it was on the losing side, agreed to discuss surrender to Aempis. Valuser'rh, not wanting peace so that it could continue to hammer Aempis on their homefront, launched a fly-by-night operation to destroy a major Human city. They chose Jerusalem, igniting a massive spell of nuclear force over it. This event was known as the Lancing of Jerusalem.
It was a miracle that the the diplomats were able to uncover that neither side had launched the attack, otherwise the war would have continued.