Holy Grail War

A term for a competition to acquire the Holy Grail.
So long as the prize has the same abilities as the Holy Grail of legend, even a battle for a fake will be deemed a Holy Grail War.
However, the Fuyuki Holy Grail War is particularly special, as the Servant System that turns Heroic Spirits into familiars is something unique to Fuyuki itself.
The preparations and arrangements were all handled by the Association, and they are more or less in charge of running the ritual. But, since it’s a battle for the “Holy Grail” the Church refused to just sit idly by.
“It matters not if it is real or fake. It is our duty to manage the Holy Grail.”
With that, they dispatched a supervisor to Fuyuki, scheming to snatch away the Holy Grail from the magi should an opening present itself.
…Basically, the game software was developed by magi affiliated with the Association, but the rights to the hardware that runs the game belong to the Holy Church. Really, it’s a pretty unreasonable setup.

Fate/side material: Fate Encyclopedia

The Holy Grail War is the competition and system employed by Magus who seek the Holy Grail. It takes place about once every 60 years in Fuyuki City, Japan. Fate/Zero depicts the Fourth Holy Grail War. The seven Masters selected by the Holy Grail and their seven Servants duke it out in a battle royal until only one pair is left standing. Only the victor can obtain the Holy Grail, which is capable of granting any wish. The Holy Grail War system was created 200 years ago by the Three Founding Families as a massive magecraft ritual to summon the Holy Grail. The First Holy Grail War lacked a proper system and rules, and the ritual ultimately ended in failure. The system was refined over the first three wars, taking place over a span of 200 years, to achieve the current, systematic Holy Grail War system.

Fate/Zero Animation Guide I: Glossary of the holy grail war I

“Many magi of the world. Listen.
When thou illuminates the world with thy desire,
Thou shalt become the criminal which bears the name of the Savior.
No matter what era, no matter how long time continues to flow, achieving the summit through battle is the providence of man.

To all magi who were beckoned by the Moon to its cyber world.
Thou must exceed thyself and prove thee be the strongest.
The throne of SE.RA.PH is,
Bound to only answer the strongest of wishes———”

The Holy Grail War created by Moon Cell.
This is the fight for survival between 128 Masters that takes place on the seven seas virtual stage that was created inside the Moon.
Moon Cell regularly summons and gathers humans from Earth, and makes them compete for the right to use the power of Moon Cell for just once.
The competition is carried out in tournament style, and the 128 Masters fight single elimination battles until there is only one standing in the end.
This competition is a death game where half the participants are eliminated each round. Once you have entered the Holy Grail War, the only way to return home alive is to become the ultimate victor of the tournament.
Moon Cell does not desire “the strongest individual.” This battle for survival is just an object of observation, and functions as a method to adjust and calibrate the metrics used to measure humans.
Of course, regardless of what the victor wishes for, and what kind of conclusion their wish may bring about, everything is recorded in order to better understand humans.

Fate/EXTRA Material: Encyclopedia of Fate/EXTRA

A battle between seven magi (Masters) and seven Heroic Spirits (Servants), where they fight to obtain the right to use the omnipotent wish-granting Holy Grail. The Holy Grail War that takes place in the Imperial Capital during the final stages of World War 2 is the stage for Fate/Type Redline’s story.

Fate/type Redline: Fate/type Redline Glossary