"It is with deep sadness that we share the news of the passing of Donald Rumsfeld, an American statesman and devoted husband, father, grandfather and great grandfather," his family said in a statement on Wednesday. "At 88, he was surrounded by family in his beloved Taos, New Mexico."
They added: "History may remember him for his extraordinary accomplishments over six decades of public service, but for those who knew him best and whose lives were forever changed as a result, we will remember his unwavering love for his wife Joyce, his family and friends, and the integrity he brought to a life dedicated to country."
Rumsfeld, an Illinois native, Princeton University graduate, and Navy veteran, represented a suburban Chicago congressional district in the House of Representatives from 1963 to 1969.
He was the US ambassador to NATO from February 1973 to September 1974 and the White House chief of staff under Ford from September 1974 to November 1975. He served as the defense secretary from November 1975 to January 1977.
US forces toppled the Taliban in the country and supported a new democratically elected government.
In 2002, Rumsfeld and Vice President Dick Cheney set their sights on the Iraqi dictator Saddam Hussein. A US-led coalition invaded the country the next year with the rationale of stopping him from launching attacks with weapons of mass destruction.
No such weapons were discovered. The Iraq War left the country susceptible to internal sectarian violence.
Where Rumsfeld was once praised for his leadership at the Pentagon, he soon became a lightning rod for opponents of the war.
After photos emerged of US soldiers abusing Iraqi prisoners at the Abu Ghraib prison in Baghdad, Rumsfeld was blamed.
He had approved harsh interrogation techniques for detainees, and under his leadership the country opened a special prison at the US naval base at Guantánamo Bay, Cuba. A practice of holding prisoners in indefinite detention drew international scorn from human-rights activists.
In December 2002, Rumsfeld approved a memo that authorized the "use of mild, non-injurious physical contact such as grabbing, poking in the chest with the finger, and light pushing," as well as stress positions.
A copy of the memo showed that Rumsfeld had commented on detainees standing for hours on end at the hands of US interrogators.
"I stand for 8-10 hours a day," he wrote. "Why is standing limited to 4 hours?"
Rumsfeld resigned after the 2006 midterm elections, in which Republicans lost their congressional majorities as Americans began to turn against the war.