Historically, there was no position called "chief of staff" till the early 1960s. Most of the duties of such a person used to be filled by the president's private secretary or by his special assistant. The White House staff was much smaller in the era before the rise of cable TV and the internet, and managing the president's schedule and his appearances was evidently easier to accomplish. While a number of presidents had a presidential assistant, he first time a president seems to have had a "chief of staff" was in 1961-62.
Norton A. Schwartz, the 19th and current US Air Force Chief of Staff (2010).
Lieutenant General Adna Chaffee who was the second US Army Chief of Staff.
Chief of Staff is a proper title.
The current White House Chief of Staff is Rahm Emanuel.
Vandenburg I believe.
He is the Deputy chief of staff of the US Army
General John Dale Ryan, 7th Chief of Staff, USAF and General Michael E. Ryan, the 16th Chief of Staff, USAF.
The title is 'Chief of Staff.' But one might say or write "...the Chief of Staff's responsibility."
Lieutenant General Samuel B. M. Young.
mind
General Omar Bradley.
William Daley.