The monologue at the start of the A-Team went like this:
“In 1972, a crack commando unit was sent to prison by a military court for a crime they didn’t commit. These men promptly escaped from a maximum security stockade to the Los Angeles underground. Today, still wanted by the government, they survive as soldiers of fortune. If you have a problem, if no one else can help, and if you can find them, maybe you can hire the A-Team.”
But what exactly was the “crime they didn’t commit”?
After some searching and watching of several episodes, I found out that in 1972, in an effort to bring the Vietnam war to an end, the A-Team, under orders from a Colonel Morrison, robbed the Bank of Hanoi. However, due to a double cross, Colonel Morrison was murdered and his headquarters burnt to the ground, and so no proof existed that the A-team were acting under orders. Because of this the A-Team were sent to prison by a military court.
So there you go.