Gate and thus Chaldea fought there.

The year was 2017, after Chaldea had saved the world from a world ending disaster, they have begun to reconstruct the world with the help of the servants that Ritsuka Fujimaru had summoned. Unbeknownst to them, an unknown danger popped up in Fuyuki, Japan and it seemed like another danger that Ritsuka, Mash Kyrielight, and the Servants of Ritsuka have to deal with. But this time, the opponents that they're dealing with are from another dimension. Since Ritsuka and Mash have been dealing with magical stuff in their lifetime, they're expertise in this should prove helpful in the time of aid in Fuyuki.