During his confinement , Colonel Hall heightened his mental and visualization skills to develop a virtual golf course in his mind .
Colonel Hall was held prisoner for seven - and a-half years , until his release on February 12 , 1973 .
During Colonel Hall 's confinement , Colonel Hall heightened his mental and visualization skills to develop a virtual golf course in his mind .
Colonel Hall was held prisoner for seven - and a-half years , until his release on February 12 , 1973 .