Lyndon Johnson did not blend easily into a crowd. At six feet three inches tall and more than two hundred pounds, he was a towering figure, physically and otherwise, and when he came upon a group of people, his instinct was to address them, or to throw himself into the scrum and become its focus, its center of gravity. But on July 16, 1969, in the reviewing stands at Cape Kennedy, in Florida, Johnson appeared to be just another spectator—looking up at the sky, squinting behind his sunglasses, as the Saturn V rocket lifted off, carrying the Apollo 11 spacecraft toward its destination.

In an interview five days later, when the astronauts were on their way home from the moon, the CBS News anchor Walter Cronkite referred to former President Johnson as “the Father of the Program,” but the label never stuck. Few understood then—and perhaps fewer understand now—that no one did more than L.B.J. to commit the U.S. to landing men on the moon and returning them safely to earth. It was John F. Kennedy, of course, who issued that call, but only after Johnson had led the charge for years.

On October 4, 1957, within hours of learning that the Soviet Union had put the first satellite, the Sputnik, into orbit, Johnson—then the Senate Majority Leader—seized on the issue of space exploration. Before the evening was out, he was working the phones, talking to aides, sketching out plans for an investigation of the anemic U.S. program. George Reedy, a member of Johnson’s staff, advised him that the issue could “blast the Republicans out of the water, unify the Democratic Party, and elect you President. . . . You should plan to plunge heavily into this one.”

So Johnson plunged in—while Kennedy, his Senate colleague and potential rival for the Democratic nomination in 1960, hung back, showing little interest in space. (When Kennedy talked about “Russian satellites,” he usually meant Poland, East Germany, Czechoslovakia.) In November, 1957, after the Soviets sent a dog, Laika, into orbit (without bringing her back, alas), Johnson began congressional hearings in an “atmosphere of another Pearl Harbor,” as he himself described it. Life put him on its cover: “A MAN OF URGENCY,” the magazine said.

In January, 1958, Johnson issued a seventeen-point plan to win the “race for survival”—among them a proposal that responsibility for the space program be extracted from the bickering military branches and invested in a new, civilian agency. The idea was not Johnson’s, but he pressed it at the right time with the right degree of force. President Dwight D. Eisenhower had resisted establishing what he called, mockingly, “a great Department of Space,” but Johnson, and circumstance, wore him down. NASA was their joint creation.

This was not enough to win Johnson the nomination. Neither did it play a role in his selection as Kennedy’s Vice-President. Still, in 1960, Kennedy embraced Johnson’s use of space as a cudgel—and his contention that “control of space means control of the world.” Every Soviet “first” in space, and every U.S. missile that blew up on the pad, made it harder for the Republican nominee, Vice-President Richard Nixon, to argue that the country was keeping up with the Soviet Union technologically—or militarily. “Can you tell me,” Kennedy demanded at a rally in Wichita, Kansas, “how any citizen can vote for a political party and leadership which permits us to be second in space?” Yet Kennedy offered no plan to be first; and, once elected, he left that question to L.B.J. and moved on to more pressing concerns, of which there were plenty.

As chairman of the National Aeronautics and Space Council, a White House advisory group, Johnson moved quickly to “dominate Washington space activities,” as Aviation Week approvingly put it. Kennedy, preoccupied with Cuba, Southeast Asia, and other matters, paid the issue little mind—until April 12, 1961, when a Russian, Yuri Gagarin, became the first person in space. “If somebody can just tell me how to catch up,” Kennedy beseeched his staff. That somebody was Johnson, who made the case for a manned lunar mission—America’s only chance, he believed, to leapfrog the Soviets. In late April, he sent Kennedy a memo billed as an evaluation of the space program, but it was not that; it was a piece of advocacy, a one-sided case for “aggressive” action. “This country should be realistic,” Johnson warned J.F.K.; other nations “will tend to align themselves with the country which they believe will be the world leader—the winner in the long run.” And like it or not, Johnson added, “dramatic accomplishments in space” were the mark of world leadership.

Kennedy yearned for a way out of the race. Its cost, he thought, was unconscionable; it promised fewer benefits to humanity, he said more than once, than desalinating ocean water would. But Gagarin changed his calculus. Seeing no way out, he reached for a way to win.

Many voices urged Kennedy toward the moon—but none more insistently, or effectively, than his Vice-President. In the weeks after Gagarin’s flight, Johnson brought senior officials to the White House to consider “not whether, but how—not when, but now.” When the NASA administrator, James Webb, questioned if Americans were actually prepared to do—and spend—what it would take to put their countrymen on the moon, Johnson told him to “get guts enough” to back the plan. Webb did; and so, in an Oval Office meeting on May 10th, did the President. L.B.J. missed that meeting. He was on a plane to South Vietnam, sent there by Kennedy to reaffirm U.S. support for its deeply troubled regime. But Johnson’s presence in the meeting wasn’t needed; he and his position had already prevailed. On May 25th, Kennedy stood before Congress and announced the goal that Johnson had helped shape.

From that moment on, Johnson’s role receded. He continued to give speeches about space, visit space facilities, and contrive to get his picture taken with the Mercury astronauts. But his responsibility, now, was to promote Kennedy’s agenda, not to take credit for it. Years later, as President himself, Johnson struggled to be seen as more than a steward of the slain leader’s program. “I conducted the first investigations in the space field as a member of the Senate,” Johnson pointed out in a speech in 1965. But in July, 1969, in his interview with Walter Cronkite, he did not contest what the nation understood: it was President Kennedy, Johnson acknowledged, who “set our goal . . . and he succeeded.”