His leadership helped shape US foreign policy in the last years of the 20th century. He was 84.

Colin Powell was former President George W. Bush’s first Cabinet selection when he was announced as the 43rd President’s nomination for secretary of state, and with his expertise in foreign policy and widespread popularity, he was unanimously confirmed by the Senate.

He shared Bush’s reluctance to project military strength across the globe, a view that was quickly displaced by the terrorist attacks of Sept. 11, 2001. As Bush’s top diplomat, he was tasked with building international support for the War on Terror, including the Afghanistan War, but it was his involvement in the administration’s push for intervention in Iraq, over the concerns of many of America’s longtime allies, for which his tenure at State would become best known.

In February 2003, Powell delivered a speech before the United Nations in which he presented evidence that the US intelligence community said proved Iraq had misled inspectors and hid weapons of mass destruction.

Inspectors, however, later found no such weaponry in Iraq, and two years after Powell’s UN speech, a government report said the intelligence community was “dead wrong” in its assessments of Iraq’s weapons of mass destruction capabilities before the US invasion.

But the damage was already done — to both Iraq, which the US went to war with just six weeks after Powell’s speech, and to the reputation of the once highly popular statesman, who was reportedly told by Cheney before the UN speech: “You’ve got high poll ratings; you can afford to lose a few points.”

Powell, who left the State Department in early 2005 after submitting his resignation to Bush the previous year, later called his UN speech a “blot” that will forever be on his record.

“I regret it now because the information was wrong — of course I do,” he told CNN’s Larry King in 2010. “But I will always be seen as the one who made the case before the international community.”

“I swayed public opinion, there’s no question about it,” he added, referring to how influential his speech was on public support for the invasion.

In his 2012 memoir, “It Worked for Me,” Powell again acknowledged the speech, writing that his account of it in the book would likely be the last he publicly made.

“I am mad mostly at myself for not having smelled the problem. My instincts failed me,” he wrote, referring to the report he used that contained faulty evidence of supposed Iraqi WMDs. “It was by no means my first, but it was one of my most momentous failures, the one with the widest-ranging impact.”

“The event will earn a prominent paragraph in my obituary,” Powell wrote.