In 1274 (date in the game incorrectly given as 1271) the Northern kings, sorcerers, sorceresses and Nilfgaardian ambassador, Shilard Fitz-Oesterlen, assemble in Loc Muinne. The assembly was to decide the future borders and powers in the Northern Kingdoms, as well as restoring the Council and the Conclave of sorcerers. However it eventually turns out the regicides and pinning the blame on the Lodge was ordered by Emhyr var Emreis himself and carried out by Letho.
For now, the fate of the war is unknown, except for that the Nilfgaardian army crossed the Yaruga and is steadily marching north, using the chaos of Foltest's, Demevand's and potentially Stennis's or Henselt's death to their advantage.
From the official wiki page.
Check this one out.
http://witcher.gamepedia.com/Timeline
Notice that, according to TW2 memory cutscenes, Geralt and Letho met in 1270.
And after that Geralt was forced to join the Wild Hunt. He rode with them for 2 years if I am not mistaken. Which brings us to year 1272, at the start of the Witcher.
Just a silly mistake that happened in TW1 timeline and nobody fixed afterwards.