Alexander Haig was a four-star general who served as a top adviser to three US presidents and had presidential ambitions of his own.
His long and decorated military career launched the Washington career for which he was better known, including top posts in the Nixon, Ford and Reagan administrations.
He never lived down his televised response to the 1981 assassination attempt on President Ronald Reagan.
Hours after the shooting, Mr Haig, who was then Secretary of State, went before the cameras intending, he said later, to reassure Americans that the White House was functioning.
"As of now, I am in control here in the White House, pending the return of the vice president," he said.
Some saw the comment as an inappropriate power grab in the absence of Vice President George HW Bush, who was flying back to Washington from Texas.
In his book, Caveat, Mr Haig later wrote that he had been "guilty of a poor choice of words and optimistic if I had imagined I would be forgiven the imprecision out of respect for the tragedy of the occasion".
Mr Haig ran unsuccessfully for president in 1988, when Mr Bush won the Republican nomination.
"I think of him as a patriot's patriot," said George P Shultz, who succeeded Mr Haig as the country's top diplomat in 1982.
"No matter how you sliced him it came out red, white and blue. He was always willing to serve."
Born on December 2, 1924, in the Philadelphia suburb of Bala Cynwyd, Alexander Meigs Haig spent his boyhood days dreaming about a career in the military. With the help of an uncle who had congressional contacts, he secured an appointment to the US Military Academy at West Point in 1943.
After seeing combat in Korea and Vietnam, Mr Haig - an Army colonel at the time - was tapped by Henry Kissinger to be his military adviser on the National Security Council under President Richard M Nixon. He "soon became indispensable," Mr Kissinger later said of his protege.
Mr Nixon promoted Mr Haig in 1972 from a two-star general to a four-star rank, passing over 240 high-ranking officers with greater seniority.
The next year, as the Watergate scandal deepened, Mr Nixon turned to Mr Haig and appointed him to succeed HR Haldeman as White House chief of staff. He helped the president prepare his impeachment defence - and, as Mr Nixon was preoccupied with Watergate, Mr Haig handled many of the day-to-day decisions normally made by the chief executive.
On Mr Nixon's behalf, Mr Haig also helped arrange the wiretaps of government officials and reporters, as the president tried to plug the sources of news leaks.
About a year after assuming his new post as Mr Nixon's right-hand man, Mr Haig was said to have played a key role in persuading the president to resign. He also suggested to President Gerald Ford that he pardon his predecessor for any crimes committed while in office - a pardon which is widely believed to have cost Mr Ford the presidency in the 1976 against Democrat Jimmy Carter.
Years after serving as one of Mr Nixon's closest aides, Mr Haig would be dogged by speculation that he was "Deep Throat" - the shadowy source who helped Washington Post reporters Bob Woodward and Carl Bernstein break the Watergate story. Mr Haig denied it, repeatedly, and the FBI's Mark Felt was eventually revealed as the secret source.
Following Mr Nixon's resignation, Mr Haig stayed with the new Ford administration for about six weeks, but then returned to the military as commander in chief of US forces in Europe and supreme allied commander of Nato forces - a post he held for more than four years. He quit during the Carter administration over the handling of the Iran hostage crisis.
Mr Haig briefly explored a presidential run in 1979, but decided he did not have enough support and instead took a job as president of United Technologies - his first job in the private sector since high school.
When Ronald Reagan became the 40th president of the United States, Mr Haig returned to public service as his Secretary of State, and declared himself the "vicar of American foreign policy".
His 17-month tenure was marked by turf wars with other top administration officials - including Defence Secretary Caspar Weinberger and national security adviser William Clark.
Two months into the new administration, Mr Haig was portrayed as pounding a table in frustration when the chairmanship of a crisis management team went to Mr Bush. Despite the clashes, Mr Haig received high praise from professional diplomats for trying to achieve a stable relationship with the Soviet Union.
In his book, Mr Haig said he had concluded during a 1982 trip to Europe with the president that the "effort to write my character out of the script was under way with a vengeance". He resigned days later.
Describing himself as a "dark horse", Mr Haig sought the Republican presidential nomination for the 1988 elections. On the campaign trail, he told supporters about his desire to "keep the Reagan revolution alive", but he also railed against the administration's bulging federal deficit - calling it an embarrassment to the Republican Party.
Mr Haig dropped out of the race just days before the New Hampshire primary.
During his career in public service, Mr Haig became known for some of his more colourful or long-winded language. When asked by a judge to explain an 18-and-a-half-minute gap in one of the Nixon White House tapes, Mr Haig responded: "Perhaps some sinister force had come in."
And later, when he criticised Mr Reagan's "fiscal flabbiness", Mr Haig asserted that the "ideological religiosity" of the administration's economic policies were to blame for doubling the national debt to 2 trillion dollars in 1987.