Dick Cheney, the hard-charging conservative who became one of the most powerful and polarizing vice presidents in U.S. history and a leading advocate for the invasion of Iraq, has died at age 84.

Political analyst Scott Lucas said he would be "remembered primarily for the 2003 Iraq war, which, in one way was the pinnacle of American power."

Cheney died Monday due to complications of pneumonia and cardiac and vascular disease, his family said Tuesday in a statement.

The quietly forceful Cheney served father and son presidents, leading the armed forces as defense chief during the Persian Gulf War under President George H.W. Bush before returning to public life as vice president under Bush's son George W. Bush.

Cheney was, in effect, the chief operating officer of the younger Bush's presidency.

He had a hand, often a commanding one, in implementing decisions most important to the president and some of surpassing interest to himself — all the while living with decades of heart disease and, post-administration, a heart transplant.

Cheney consistently defended the extraordinary tools of surveillance, detention and inquisition employed in response to the attacks of September 11, 2001.

Bush called Cheney a “decent, honorable man” and said his death was “a loss to the nation.”

Years after leaving office, Cheney became a target of President Donald Trump, especially after his daughter Liz Cheney became the leading Republican critic and examiner of Trump's desperate attempts to stay in power after his 2020 election defeat and his actions in the January 6, 2021, riot at the Capitol.

"Liz Cheney was a Republican who sacrificed her career, who was absolutely vilified by Trump for standing up and saying, whether Republicans or Democrats, the system must be defended," said Lucas.

A survivor of five heart attacks, Cheney long thought he was living on borrowed time and declared in 2013 he awoke each morning "with a smile on my face, thankful for the gift of another day,” an odd image for a figure who always seemed to be manning the ramparts.

In his time in office, no longer was the vice presidency merely a ceremonial afterthought.

Instead, Cheney made it a network of back channels from which to influence policy on Iraq, terrorism, presidential powers, energy and other cornerstones of a conservative agenda.