The Despenser War "totally changed the political scene in England". Edward's victory provided the catalyst for the disintegration of the baronial oligarchy giving the King the opportunity to resume the regal powers the Ordainers had denied him since they presented their Ordinances to him in 1311. Roger Mortimer was imprisoned in the Tower of London after his surrender at Shrewsbury and some of his supporters, including William Trussell, continued to raid Despenser lands. In August 1323 Mortimer escaped and attempted to break other Contrariants out of Windsor and Wallingford Castles. He eventually fled to France where he was later joined by Queen Isabella, who was ostensibly on a peace mission, but was actually seeking assistance from her brother, King Charles IV of France to oust the Despensers. Mortimer and Isabella obtained the necessary help in Flanders and in 1326 the successful Invasion of England was launched. This invasion led to the executions of the two Despensers, the deposition and killing of Edward II, and the seizure of authority by Queen Isabella and Roger Mortimer, who became the de facto rulers of England from 1327 to 1330. Mortimer was hanged, drawn and quartered in November 1330 by the order of Isabella's son King Edward III after he ousted his mother and Mortimer from power and assumed personal rule.
Question: How many years was Mortimer imprisoned in the tower of London?
Answer: 12