Streets of Intrigue
The Coalescence is divided into two separate events the first being the actual coalescence and the second being The Grand Coalescence.
The Coalescence was a gradual event that took place over the first five month of 1850. During that time period there would be small pockets of peoples from other dimensions that would cross over to Terra. Many of the Ephrexans and Striders were killed for the their appearance before they could explain themselves, but many Cheshireans blended into society quickly due to their appearance being so similar to Terrans.
The Grand Coalescence
This is the event that sparked The Coalescent War for Dominance between the Terrans and the Striders and Ephrexans. During this event huge white rifts opened up all around Terra other races began pouring out of them. The event was very jarring because of the appearance of the Ephrexans and Striders many religious figures declared it to be The End of Days. Those ideas were a drastic over statement of what had actually happened which was the dawning of a new age over Terra.