True and False Holy Grail Wars

The True Holy Grail War (本当の聖杯戦争) and False Holy Grail War (偽りの聖杯戦争) are two simultaneous Holy Grail Wars held in Snowfield in America,

False Holy Grail War
The False War is a primer for the true war, gathering enough energy by summoning six Servants. America based on the one in Fuyuki. Rather than fighting for a Holy Grail, the war is over a "False Grail", making the ritual hard to predict compared to that of Fuyuki. While it seems that the immense scale of the preparation for the ritual would have required a magi family of the caliber of a Great House like the Einzberns, the "Initiator" of the Holy Grail War has not appeared, nor do they give off any such presence of magi of their theorized stature.

The definition of “Summoning Rituals” is vague at best due to the flawed system, as shown by the summoning of Rider. After the fifth Servant is summoned, the False Grail wishes for the materialization of the sixth Servant, even through brutal force.