‘This is the result of the photography taken Sunday, sir. There’s a medium-range ballistic missile launch site and two new military encampments ... in West Central Cuba. The launch site at one of the encampments contains a total of at least 14 canvas-covered missile trailers, measuring 67 feet long and more than nine feet in width.”

On a Tuesday morning in October 1962, these chilling words informed President Kennedy and his advisors that the Soviet Union was constructing nuclear missile sites in Cuba. Thanks to recording devices established and activated by JFK, we can actually hear CIA briefer Marshall Carter and deliver this precise analysis of U.S. spy plane photos. Their tone appears calm and measured, yet this briefing would light the touch paper for the Cold War’s most dramatic crisis. Nuclear missiles now lay in place merely 90 miles off the U.S. coast, contrary to the express assurances of Soviet Premier Khrushchev and in the face of repeated warnings from President Kennedy in preceding months.

These missiles presented a dramatic challenge to the precarious balance of Cold War power, and the next 13 days would see a dangerous stand-off between two nuclear superpowers with a combined arsenal of some 4,000 warheads. Before the crisis was resolved, one of these warheads would be ordered for launch.

Robert F. Kennedy, JFK’s younger brother, was 36 years old at the time. One of the youngest attorneys general ever appointed, RFK was also the president’s de facto chief of staff and most trusted advisor. Known as “that terrier of a man” by some in the Kennedy administration, RFK was profoundly committed to his brother’s success. On the campaign trail for his brother years earlier he had remarked, “I don’t care if anyone likes me, so long as they like Jack.” He carried this temperament through to the president’s administration, doggedly pursuing his brother’s objectives, ever ready to cut through departmental etiquette to ask forceful questions and to challenge the answers.

By October 1962, he had already proved himself indispensable to the president. It was to his younger brother that the president had turned after a botched invasion of Cuba in 1961 (the Bay of Pigs fiasco), appointing him head of a task force examining the causes of the disaster. A year later, it was no surprise that RFK was one of the first to be notified of the missiles, receiving an urgent phone call from the president a few hours ahead of the CIA briefing.

In the coming days and weeks RFK would make a unique and indispensable set of contributions to resolving the crisis. We are now able to follow these contributions in rich detail, thanks to the remarkable in-the-room access provided by the White House tape recordings, as well as new archival sources recently declassified.

First, RFK went after the raw data. His personal files on the crisis hold as many as 3,584 documents directly reviewed by him over the period. Immediately after hanging up the phone to his brother, he coordinated a private briefing with the CIA. Joining cabinet discussions later that morning, RFK was already extremely well-briefed on the missile sites, their disposition and readiness.

Such preparation was an RFK trademark, especially where it required out-of-the-box thinking. In his private notes on the Bay of Pigs disaster, RFK had judged “underestimation” of Castro’s forces as a key failing of the Kennedy administration. Determined not to repeat the mistake, RFK was one of only two presidential advisors to predict the installation of missile sites in Cuba, warning his brother of the possibility over a year before the crisis.

He then took active measures to prepare for the possibility, instructing the Departments of State and Defense to investigate possible responses, whilst also outlining his own proposals in interdepartmental security briefings. These proposals were remarkably prescient of those actually debated and subsequently chosen during the Cuban Missile Crisis. As a direct result of RFK’s proactive, terrier-like energy, the key government departments tasked with handling the Cuban missile crisis had been remarkably well-prepared in contingency thinking and intelligence.

Perhaps even more importantly, so had the president’s closest advisor. As the crisis developed, RFK continued to seek new information and advice, acting as his brother’s eyes and ears—able to go where he could not, to source frank perspectives unhindered by presidential deference. At times this meant spotlighting another advisor’s counsel in a cabinet meeting; at others summarizing a loud mess of opinions into a coherent range of actionable options for the president.

In a few unique circumstances, it even meant playing up a blunter edge to his persona, asking the sort of direct questions the president could not. In one remarkable exchange during the crisis, apparent in the tapes, the president can actually be heard whispering instructions to RFK on a difficult question he wanted put to the head of the CIA. RFK also held a number of pivotal one-on-one conversations with fellow advisors during the crisis, privately relaying these back to the president in a number of off-the-record discussions.

Indeed, we know, from diary entries, references in official memoranda and the tapes themselves, that RFK met privately with the president throughout the crisis. These were frank one-on-ones that gave the president an opportunity to talk through options freely, and RFK the chance to bring new information and advice to the president outside of busy group meetings. As Kenneth O”Donnell, JFK’s special assistant at the time, would later remark, “Bobby could always reach him.” On one evening at the height of the crisis, the two brothers even discussed JFK’s possible impeachment.

In the first days of the crisis, whilst other presidential advisors were still processing the shocking news, RFK jumped far ahead, coldly calculating and interrogating the possible U.S. response. He insisted that an invasion remain on the table, and even pushed for a reduction in the lead time required to initiate one. Until recently this approach was held up as evidence for a belligerent, hawkish advisor, promoting the sort of military action that would have led to dangerous escalation.

Yet declassified private notes, and a closer understanding of the brother’s intimate relationship, now support a more holistic view of RFK. He saw his role as pressing for all alternatives, regardless of where they might lead. In the words of McGeorge Bundy, national security advisor at the time, RFK’s function was “to go and prod and poke people into doing their best, and staying with the problem, and not giving up until we got a better answer.” RFK would subsequently put his weight behind the famous blockade plan, a naval quarantine of Cuba designed to pressure the Soviets to remove the missiles.

Although he did not conceive the plan, he was instrumental in convincing other advisors of its merits and, ultimately, the president. In both cases he was able to do so because he was seen as balancing resolve with restraint, bridging the more forceful approach advocated by the military and Joint Chiefs with the optimistic diplomacy pushed by dovish advisors such as U.N. Ambassador Adlai Stevenson.

RFK took this balanced approach into secret, back-channel meetings with the Soviet ambassador, Anatoly Dobrynin. Frustrated by the equivocations of the State Department, the president sought a quick resolution to the crisis through more direct channels. He personally tasked RFK to meet with Dobrynin in an attempt to convey the voice of the president directly to Soviet Premier Khrushchev. The President trusted Khrushchev would interpret RFK in this way, having deployed him in a similar fashion a year earlier.

He had also made RFK’s privileged role clear to Khrushchev via the Soviet premier’s son-in-law Alexei Adzhubei. When asked by Adzhubei, in a private meeting, whether RFK was “No. 2 in Washington,” JFK replied that he wasn’t just “No. 2, but 3, 4, 5 and 6.” Soviet documents record this being relayed directly to Khrushchev and taken seriously, despite the jokey tone.

Before one such meeting with Dobrynin, RFK scribbled a brief note reminding himself “to emphasize danger.” Both brothers felt that only negotiation from strength would work with Soviet Premier Khrushchev, that appearances contribute to reality. RFK was successful in striking the right tone, with Dobrynin and RFK’s accounts of their meetings being surprisingly consistent. Both note RFK’s warnings of military action if the Russians did not withdraw their missiles, of “a chain reaction” that could quickly start and be very hard to stop. But beyond the words, it was Dobrynin’s trust that the president was speaking through RFK, and his instinctive grasp of the truth in RFK’s eyes, that carried such power.

As Dobrynin himself recalled, “I had no doubt that my report of this conversation turned the tide in Moscow.” This is corroborated by an account of the Presidium meeting where Dobrynin’s report was read aloud, with a recollection that it created “a state of alarm.” Likewise, Khrushchev himself, for all that he may have vacillated in the final hours between backing down and pressing on, described the report of RFK/Dobrynin’s most dramatic meeting a “culminating moment.”

RFK also knew where to intervene to get things over the line. As JFK himself once remarked, “We’ve got more guys around here with ideas. The problem is to get things done. Bobby’s the best organizer I’ve ever seen.” Take the “Trollope Ploy”; a bold strategy for navigating two very different proposals from Khrushchev as the crisis drew to the end of its second week. Each proposal was received within the space of a few hours. The first was private and conciliatory, promising to remove the missiles in return for an American assurance not to invade Cuba. The second was announced publicly, only committing to remove the missiles in return for the Americans also removing their missiles from Turkey.

This second proposal would have been incredibly difficult for President Kennedy to deliver, and a challenge to NATO unity. The Trollope Ploy was simple: that the U.S. accept Khrushchev’s first proposal while barely acknowledging receipt of the second. It has been mistakenly attributed to RFK in the past. In truth, he did not conceive the ploy—but it would not have been possible without him. The president was initially skeptical of the plan, fearful of “screwing around for another 48 hours.”

RFK took hold of the situation, assuming the leadership mantle but doing so selectively. He took the president’s chief speechwriter, Ted Sorensen, into a separate room to draft the reply alone—”to work it out for you without you being there to pick it apart,” as he said to JFK. The draft was successful, and JFK approved the ploy, simultaneously tasking RFK with making a private, highly secret assurance to Dobrynin that the missiles in Turkey would be removed “at a later date.” This assurance was kept secret, though strongly suspected by experts on the crisis, until 1989. It was fundamental to resolving the crisis—and a pivotal contribution from RFK.

RFK delivered his final-chance message to Dobrynin on the evening of October 27. At 10 AM the following morning, Radio Moscow read out a letter from Khrushchev to Kennedy. It announced the immediate withdrawal of the missiles, “to crate and return them to the Soviet Union.” Shortly after, Kennedy released his own public statement heralding the “solution of the Cuban crisis,” praising Khrushchev’s “statesmanlike decision” and promising “reciprocal measures to assure peace in the Caribbean area.” The crisis had come to a close.

There were many pivotal moments in the crisis, a good number of which cannot be attributed to statesmen. To return to the near-launch of a nuclear warhead, this was averted thanks to the deputy commander of a Russian submarine, who bravely countermanded his superior’s orders to prepare for launch. But fundamentally this was a crisis in which the wrong leaders, with the wrong advice, taking the wrong actions, could have easily tipped the world into nuclear war.

That this did not happen was a testament to both President Kennedy and Premier Khrushchev. In this context, historians must ask if President Kennedy could have succeeded without his younger brother. Who else could have conveyed a private message directly to Khrushchev, with the power of presidential voice? Would the “Trollope Ploy” be remembered merely as a cute idea that fizzled out under scrutiny? Would JFK have cracked under the pressure of presidential authority, with no steadfast confidant to rely on?

We can only look to a telling exchange between the brothers, some five months after the crisis. A committee had been convened to investigate the apparent failure of the U.S. intelligence community to predict the deployment of Soviet missiles in Cuba. Nervous about one line of inquiry, the president immediately turned to RFK. An intimate language of their own can be heard on a late-evening call, clearly rooted in a deep and abiding trust between the two brothers. One of the most successful American Presidents in history asks his younger brother: “What other ways do you have? How would you handle it?”