A secret letter from General Eisenhower that highlights the importance of Bletchley Park's intelligence operation during World War Two is going on public display for the first time.
The 'thank you' letter from Eisenhower to the chief of the Secret Intelligence Service goes on display at Bletchley Park later.
It was sent in July 1945 and David Hatch, an NSA historian, said it was recognition of the joint effort of American and British cryptologists to uncover information that could be used to defeat the Nazis.
Dr Hatch said Eisenhower would have been very much aware of the impact people at Bletchley Park had had.
Less than five years he was appointed the first commanding general of NATO and two years later, preseniden tof the USA. Both positions he used intelligence. It all traces back to the time that this letter is talking about.
Less than five years later, Eisenhower would be appointed the first Commanding General of NATO and, two years after, became the US president.
Dr Hatch said he became known for his use of intelligence. "It all traces back to the time that this letter is talking about," he said.