[1] The private secretary served as the president's de facto chief aide, in a role that combined personal and professional assignments of highly delicate and demanding natures, requiring great skill and utmost discretion.

[2] The job of gatekeeper and overseeing the president's schedule was separately delegated to the appointments secretary, as with aide Edwin "Pa" Watson.

During World War II, Roosevelt created the position of "Chief of Staff to the Commander-in-Chief" for his principal military adviser, Fleet Admiral William D.

[citation needed] In 1946, in response to the rapid growth of the U.S. government's executive branch, the position of "Assistant to the President of the United States" was established.

Andrew Card and Denis McDonough each served at least one entire presidential term of office under presidents George W. Bush and Barack Obama, respectively.

Journalist Bob Woodward, in his books All the President's Men (1974) and The Secret Man (2005), wrote that many of his sources, including Mark Felt, later revealed as "Deep Throat", displayed a genuine fear of Haldeman.