Colonel Charles Barnett, from the Services Prosecuting Authority, said outside the court:
Sgt Nightingale has now had the trial which he requested, which is his right to seek. He has now been convicted by the board.
His fine record as a soldier is a matter that will no doubt be considered carefully when the board considers his sentence.
More top news
A police community support officer who engaged in sex acts with a schoolgirl after meeting her while on duty has been jailed for five years.
A rather autumnal feel for the time of year
Police have launched an investigation after a woman found a hidden camera while in the shower at a Travelodge.