England could have faced up to 11 years in prison on the various charges. But, in a plea-bargain arrangement, the military prosecutor agreed to drop two of the counts against England -- dereliction of duty and committing an indecent act.
This is why England could escape with only two years.
It would be an overstatement to suggest that 2 years in prison is an easy sentence to serve. On the other hand, if this is the sentence delivered by the military court, it's fair to question whether this is sufficient punishment. I think a sentence of two years would send the wrong signal to the rest of world -- namely, that when it comes to physical and psychological torture, America holds other nations to a very different standard than it holds its own citizens.