Military action
After the Empire's humiliation at Rimmen, the true mettle of the Empire is put to the test when a delegation from the province of Black Marsh arrives at the White Gold Tower on the cold morning of Saturalia. The delegation wordlessly delivers to the Elder Council the signet rings of each of the Imperial governors of the province, as well as the severed tails of their loyalist Argonian advisors. They depart without a word.
Although never formally recognized, this coup goes unchallenged, and the Argonian Union is born.