James Pritchard, now a volunteer driver on aid convoys in Bosnia, is claiming damages for the extra time he spent in the forces because of a mistake on his application form.
But the 41-year-old former private, from Birkenhead, Merseyside, is also claiming further compensation because he alleges that when the error was discovered, officers attempted to cover it up and threatened him with jail if he did not "shut up and forgetit".
Christopher Pitchford QC, for the plaintiff, said: "In confining Mr Pritchard, the defendants acted oppressively and in excess of their authority. But then they further frustrated his attempts to obtain his release. They acted as judges in their own court and did not give him a proper opportunity of a hearing, deciding on correspondence that his case had no merits.
"They treated him both at civil servant level and battalion level with disdain and attributed disreputable motives to his attempts to leave. That attitude towards the plaintiff continues even today."
The complex case, which began six years ago, deals with the "minefield" of Army regulations and is expected to last at least four days before the High Court in London.
Mr Pitchford explained to the court that the "somewhat unusual" case revolved around the fact that the plaintiff's liberty had been restricted in that he was forced to serve 16 months longer than he had been led to believe was necessary, from November 1981 until March 1983, including a 10-week tour as a radio operator during the Falklands War.
Mr Pritchard, a divorcee who subsequently remarried, had started his Army career more than a decade earlier, in 1971, when he joined the Royal Armoured Corps shortly after he was rejected by the Parachute Regiment.
Three years later, he bought himself out of his 22-year term, believing that it would be the easiest way for him to rejoin and get into the Parachute Regiment, with which he had family connections.
He rejoined again the following year, successfully entering the 3rd Battalion of the Parachute Regiment, but again bought himself out in 1978 in a vain bid to save his failing marriage.
The following year, however, Mr Pritchard began efforts to join the Army for a third time, and was successful again in February 1980, with superiors believing he was committed to serve for a further three years until March 1983.
But he maintains that he had been told by recruiting officers that because of a change in Army regulations he would be able to give notice immediately upon rejoining that he wished to leave within 18 months, allowing him to transfer to the Volunteer Reserve later the following year.
On receipt of his first pay packet, however, it became clear to Mr Pritchard that he was signed up for three years despite what he had been told, and he immediately began efforts to have what he believed was a mistake rectified.
Mr Pitchford said the false imprisonment claim was based on his being subject to military orders and discipline, which prevented him from "moving freely at all times and to all places as he wished" during the time he was forced to serve against his will.
The case continues today.