Haig's long and decorated military career launched the Washington career for which he is 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, then Secretary of State Haig 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," Haig said.
Some saw the comment as an inappropriate power grab in the absence of Vice President Bush, who was flying back to Washington from Texas.
Haig died at Johns Hopkins Hospital in Baltimore, where he was surrounded by his family, according to two of his children, Alexander and Barbara. A hospital spokesman, Gary Stephenson, said Haig died at about 1:30 a.m.
In his book, "Caveat," 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."
Haig ran unsuccessfully for president in 1988.
Secretary of State Hillary Rodham Clinton said Haig "served his country in many capacities for many years, earning honor on the battlefield, the confidence of presidents and prime ministers, and the thanks of a grateful nation."
"I think of him as a patriot's patriot," said George P. Shultz, who succeeded 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 Dec. 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 U.S. Military Academy at West Point in 1943.
After seeing combat in Korea and Vietnam, Haig - an Army colonel at the time
- was tapped by Henry Kissinger to be his military adviser on the National Security Council under Nixon. Haig "soon became indispensable," Kissinger later said of his protege.
Nixon promoted 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, Nixon turned to Haig and appointed him to succeed H.R. Haldeman as White House chief of staff. He helped the president prepare his impeachment defense
- and as Nixon was preoccupied with Watergate, Haig handled many of the day-to-day decisions normally made by the chief executive.
On Nixon's behalf, 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 Nixon's right-hand man, Haig was said to have played a key role in persuading the president to resign. He also suggested to Gerald Ford that he pardon his predecessor for any crimes committed while in office
- a pardon that is widely believed to have cost Ford the presidency in 1976.
Years after serving as one of Nixon's closest aides, 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. Haig denied it, repeatedly, and the FBI's Mark Felt was eventually revealed as the secret source.
