During both the 2nd and 3rd World Wars, as well as the Korean War, hypnotism was utilized for various purposes. It was used as a medical tool, a weapon, as well as a strategic and intelligence device.
Soldiers in battle are subjected to horrors and traumatic expeiences that the layman cannot even begin to understand. Military doctors used hypnotherapy to allow their patients delve into their repressed memories and then help them deal with them. Hypnotism was also used to treat amnesia, as well as other stress and mental trauma related conditions.
Hypnosis was also used to infiltrate the enemies ranks. A doctor by the name of G.H. Estabrooks, who worked with the U.S. military during World War II, wrote in a medical journal how hypnosis was used to place an agent deep into the enemies camp by using the behavioral modification properties of hypnotism. He wrote the following, “I worked this technique with a vulnerable Marine lieutenant I’ll call Jones. Under the watchful eye of Marine Intelligence I spilt his personality into Jones A and Jones B. Jones A, once a “normal” working Marine, became entirely different. He talked communist doctrine and meant it. He was welcomed enthusiastically by communist cells, was deliberately given a dishonorable discharge by the Corps (which was in on the plot) and became a card-carrying party member.”
Hypnosis was also used by the intelligence services of the military. For example, a very sensitive piece of information needed to be relayed, but the worry about it falling into enemy hands meant that using the radio was not a viable option. And when sending via courier no printed copy, not even in code would want to be used. So the answer was to use suggestion on the soldier. The information was given to the soldier under hypnosis then, after successfully relaying the message, the hypnotist then suggested to the courier that he would never remember a single detail about the message, thus ensuring that it remained a secret forever.
Of course always remember hypnosis can force someone to act against their instincts, or morals. Forget the Manchurian Candidate, it was fiction.