Please answer a question about the following article about Dwight D. Eisenhower:

Within months of beginning his tenure as the president of the university, Eisenhower was requested to advise U.S. Secretary of Defense James Forrestal on the unification of the armed services. About six months after his appointment, he became the informal Chairman of the Joint Chiefs of Staff in Washington. Two months later he fell ill, and he spent over a month in recovery at the Augusta National Golf Club. He returned to his post in New York in mid-May, and in July 1949 took a two-month vacation out-of-state. Because the American Assembly had begun to take shape, he traveled around the country during mid-to-late 1950, building financial support from Columbia Associates, an alumni association.

What position was held by James Forrestal?
Secretary of Defense