When President Harry S. Truman signed Executive Order 9981 on July 26, 1948, calling for the desegregation of the U.S. Armed Forces, he repudiated 170 years of officially sanctioned discrimination. Since the American Revolution, African Americans had served in the military, but almost always separately from white soldiers—and usually in menial roles.

A major achievement of the post-war civil rights movement—and of Truman’s presidency—the event marked one of the first times a U.S. commander in chief used an executive order to implement a civil rights policy. It became a crucial step toward inspiring other parts of American society to accept desegregation.

Truman’s journey to signing 9981 is the story, in part, of heeding pressure from Black civil rights leaders and recognizing, pragmatically, the importance of the Black vote to his political fortunes. But it’s also the story of his overcoming his own deeply embedded racial prejudices.

In 1911, when Truman was a 27-year-old corporal in the Missouri National Guard, he wrote to his future wife, Bess Wallace: “I think one man is just as good as another so long as he’s honest and decent and not a nigger or a Chinaman… I am strongly of the opinion that negros (sic) ought to be in Africa, yellow men in Asia and white men in Europe and America.”

Truman came by these beliefs from his upbringing in Missouri, where his grandparents had owned slaves and where 60 African Americans were lynched between 1877 and 1950, the second-highest number of any state over that period outside the Deep South.

He grew up in a home that openly reviled abolitionism, Reconstruction and Abraham Lincoln. “Truman literally learned at his mother’s knee to share the South’s view of the War Between the States,” wrote William E. Leuchtenburg, a professor emeritus of history at the University of North Carolina at Chapel Hill, in 1991. “He also acquired an abiding belief in white supremacy.”

Yet when the beatings and murders of recently returned African American World War II veterans in the South captured national attention, Truman, who assumed the presidency after Franklin Roosevelt died on April 12, 1945, was moved to act.

“My stomach turned over when I learned that Negro soldiers, just back from overseas, were being dumped out of army trucks in Mississippi and beaten,” Truman said. “Whatever my inclinations as a native of Missouri might have been, as president I know this is bad. I shall fight to end evils like this.”

In response to the lynchings, and under pressure from Black civil rights groups, Truman formed the President’s Committee on Civil Rights in late 1946. It produced a report, To Secure These Rights, which condemned all forms of segregation and asked for an immediate end to discrimination and segregation in all branches of the armed services.

In 1947, Truman became the first president to address the National Association for the Advancement of Colored People (NAACP). In his speech at the Lincoln Memorial, Truman said, “It is my deep conviction that we have reached a turning point in the long history of our country’s efforts to guarantee freedom and equality to all of our citizens.”

Throughout his life, Truman made racist statements to his intimates and in private correspondence and likely never fully abandoned the attitudes of his youth. But he was an astute politician who understood the importance of the Black vote to his political fortunes. In 1940, as a U.S. Senator, he told the National Colored Democratic Association, “The Negroes’ flag is our flag, and he stands ready, just as we do, to defend it against all foes from within and without.”

Truman’s sharpening views on civil rights during his first term as president divided the Democratic Party. Conservative Southern Democrats from South Carolina, Mississippi and Alabama protested the party’s civil rights plank, walking out of the 1948 Democratic National Convention. Without the white Southern vote, Truman’s chances in the general election against Republican nominee Thomas Dewey dimmed considerably.

Despite the Dixiecrat defections, Truman’s aides convinced him that a winning coalition included Black voters, whose leaders saw the integration of the armed forces as a major election issue. Months before the election, 20 African American organizations, including the NAACP and the National Urban League, issued a “Declaration of Negro Voters,” which included desegregating the armed forces among its demands.

In the last days of the election, Truman made a campaign appearance in Harlem, marking the first time a U.S. president had visited the symbolic capital of Black America. Truman was lured there by Anna Arnold Hedgeman, an African American political operative who spearheaded his campaign’s Black outreach. According to Hedgeman’s biographer, Jennifer Scanlon, “Truman won the race, in a narrow margin nationally, thanks in part to the Black electorate and to Hedgeman.”

On March 22, 1948, Truman met with Black leaders to discuss segregation. “I can tell you the mood among Negroes of this country is that they will never bear arms again until all forms of bias and discrimination are abolished,” A. Phillip Randolph, the pioneering union organizer and civil rights leader, told the president.

At a hearing nine days later before the Senate Armed Services Committee, Randolph said, “I personally will advise Negroes to refuse to fight as slaves for a democracy they cannot possess and cannot enjoy.”

In a celebrated case taken up by the American Civil Liberties Union, Winfrid Lynn, a Black landscape gardener from New York, went to jail after he told his local draft board he would “not be compelled to serve in a unit undemocratically selected as a Negro.”

That June, Randolph informed President Truman that if he didn’t issue an executive order ending segregation in the armed forces, African Americans would resist the draft.

A month later, with an election looming and under intense pressure from civil rights leaders, Truman signed Executive Order 9981—and created the President’s Committee on Equality of Treatment and Opportunity in the Armed Forces, popularly known as the Fahy Committee, to oversee the process.

To achieve full integration, Truman needed cooperation from the military’s four branches. “I want the job done,” Truman told the committee in early 1949, “and I want it done in a way so that everyone will be happy to cooperate to get it done.”

For its part, the Army balked. “The Army is not an instrument for social evolution,” said Kenneth Royall, the Secretary of the Army, who expressed concern about the order’s adverse effect on enlistments, reenlistments and soldier morale nationwide—but especially in the South.

Truman, who would settle for nothing less than full desegregation, forced Royall into retirement after he refused to comply with the order.

It took six years to desegregate America’s armed forces. In late 1954, the deactivation of the 94th Engineer Battalion, the Army’s last all-Black unit, completed the process. Executive Order 9981 remains one of the crowning achievements of Truman’s eight years in office, a bold decision that pitted him against the southern wing of his party on this and other civil rights issues. But as postwar American society evolved, the armed forces became an important model for desegregation and equal opportunities for African Americans.

In 1998, on the 50th anniversary of Executive Order 9981, General Colin Powell, who later became America’s first Black secretary of state, spoke about the impact of Truman’s decision on his life: “The military was the only institution in all of America—because of Harry Truman—where a young Black kid, now 21 years old, could dream the dream he dared not think about at age 11. It was the one place where the only thing that counted was courage, where the color of your guts and the color of your blood was more important than the color of your skin.”