During the last two and a half years of a four-and-a-half-year tour in the Pentagon, before retiring in 1984, he was military executive to Under Secretary of the Army James Ambrose.

Brownlee became the 27th Under Secretary of the Army on 14 November 2001, following his nomination by President George W. Bush and confirmation by the United States Senate.

In March 1996, Brownlee was designated staff director of the Senate Committee on Armed Services by then chairman, Sen. Thurmond.

In January 1999, he was designated staff director for then chairman, Sen. Warner, serving until November 2001 when he was confirmed as the Under Secretary of the Army.

From 1987 to 1996, he was a professional staff member responsible for Army and Marine Corps programs, special operations forces and drug interdiction policy and support.