Originally Posted by
Kareeah_Indaga
Citation needed. While we know they were on the losing side of the Great War, we know the Blades won enough minor victories that the Thalmor still consider them a threat. We also know that the Blades no longer had a direct line to the Emperor, as the Mede Dynasty replaced them with the Penitus Oculatus, so they were fighting with a handicap. And on top of that the area protected by the Blades got hit by more in the way of disasters (succession crisis right after the Oblivion Crisis, Umbriel, the fall of Baar Dau and the Red Year) than the Thalmor prior to the Great War.
No indication whatsoever that their loss was due to bad information.