He presided over the creation of the first UN peacekeeping forces in Egypt (the UNEF) and the Congo (the ONUC) and personally intervened to defuse or resolve diplomatic crises.

Hammarskjöld's second term was cut short when he died in a plane crash while en route to cease-fire negotiations during the Congo Crisis.

Hammarskjöld was and remains well regarded internationally as a capable diplomat and administrator, and his efforts to resolve various global crises led to him being the only posthumous recipient of the Nobel Peace Prize.

British Foreign Secretary Anthony Eden was strongly in favor of Hammarskjöld and asked the United States to "take any appropriate action to induce the [Nationalist] Chinese to abstain".

He made a point of visiting every UN department to shake hands with as many workers as possible, eating in the cafeteria as often as possible, and relinquishing the Secretary-General's private elevator for general use.

He was also actively engaged in smaller projects relating to the UN working environment; for example, he spearheaded the building of a meditation room at the UN headquarters, where people can withdraw into themselves in silence, regardless of their faith, creed, or religion.

[30] During his term, Hammarskjöld tried to improve relations between Israel and the Arab states, frequently playing the role of a mediator between David Ben-Gurion and Gamal Abdel Nasser.

[31] Other highlights include a 1955 visit to China to negotiate the release of 11 captured US pilots who had served in the Korean War,[8] the 1956 establishment of the United Nations Emergency Force, and his intervention in the 1956 Suez Crisis.

The objective was, citing the memoirs of Soviet leader Nikita Khrushchev, to "equally represent interests of three groups of countries: capitalist, socialist and recently independent".

Hammarskjöld's refusal to place peacekeepers in the service of Lumumba's constitutionally elected government provoked a strong reaction of disapproval from the Soviets.

[34] On 18 September 1961, Hammarskjöld was en route to negotiate a cease-fire between United Nations Operation in the Congo forces and Katangese troops under Moise Tshombe.

[45] In 2014, newly declassified documents revealed that the American ambassador to the Congo sent a cable to Washington D.C. and in it, he wrote his suspicion that the plane could have been shot down by Belgian mercenary pilot Jan Van Risseghem, commander of the small Katanga Air Force.

[40] On 16 March 2015, United Nations Secretary-General Ban Ki-moon appointed members to an Independent Panel of Experts which was established for the purpose of examining new information which was related to Hammarskjöld's death.

The three-member panel was led by Mohamed Chande Othman, the Chief Justice of Tanzania, and it included Kerryn Macaulay (Australia's representative to the International Civil Aviation Organization) and Henrik Larsen (a ballistics expert from the Danish National Police).

[48][49][50] In an interview with Swedish historian Leif Hellström, van Risseghem claimed that he was not in southern Africa at the time the crash happened, and dismissed the idea of his involvement.

[50] A document which was found in France amidst the Fonds Foccart (National Archives in Pierrefitte) in November 2021 is a death warrant for Hammarskjöld that contained the acronym OAS, the secret organization which was nestled in the French army at the time of Algeria's war for independence.

The document reads: "It is high time to put an end to his harmful intrusion ... this sentence common to justice and fairness to be carried out, as soon as possible".

In the talk, Hammarskjöld declared: But the explanation of how a man should live a life of active social service in full harmony with himself as a member of the community of spirit, I found in the writings of those great medieval mystics [Meister Eckhart and Jan van Ruysbroek] for whom 'self-surrender' had been the way to self-realization, and who in 'singleness of mind' and 'inwardness' had found the strength to say yes to every demand which the needs of their neighbours made them face, and to say yes also to every fate life had in store for them when they followed the call of duty as they understood it.

[54] This diary was found in his New York house, after his death, along with an undated letter addressed to then Swedish Permanent Under-Secretary for Foreign Affairs, Leif Belfrage [sv].

[55] Markings was described by the late theologian Henry P. Van Dusen as "the noblest self-disclosure of spiritual struggle and triumph, perhaps the greatest testament of personal faith written ... in the heat of professional life and amidst the most exacting responsibilities for world peace and order".

[57]Markings is characterised by Hammarskjöld's intermingling of prose and haiku poetry in a manner exemplified by the 17th-century Japanese poet Basho in his Narrow Roads to the Deep North.

[58] In his foreword to Markings, W. H. Auden quotes Hammarskjöld as stating: In our age, the road to holiness necessarily passes through the world of action.

[59]Hammarskjöld's interest in philosophical and spiritual matters is also proven by the finding of Martin Buber's main work I and Thou, which he was translating into Swedish, in the wreckage after the plane crash.

[61] Brian Urquhart's biography of Hammarskjöld addressed what Israel Shenker described in his The New York Times review as "the oft-discussed question of Hammaskjöld's sexuality".

[62] Despite Urquhart concluding the rumours were inaccurate, Larry Kramer included Hammarskjöld in the "I belong to a culture" speech in his 1985 play The Normal Heart.

[63][64] In 1974, the Australian-British composer Malcolm Williamson, Master of the Queen's Music, wrote his Hammarskjöld Portrait for soprano and string orchestra.

The text was taken from Vägmärken, and the work's first performance took place on 30 July 1974, at a Royal Albert Hall Proms Concert, with the soprano Elisabeth Söderström, and the BBC Symphony Orchestra conducted by John Pritchard.

In 1985, Hammerskjöld was one of the names mentioned in the "I Belong to a Culture" speech in Larry Kramer's play The Normal Heart, where the protagonist includes him in a list of 24 historical gay figures.

[63][64] In the 2016 film The Siege of Jadotville, depicting the events of the Congo Crisis,[83] Hammarskjöld's plane (incorrectly a DC-4) is purposely shot down by a fighter jet only used by American forces at the time (it's likely this was for production reasons, just as a DC-4 stood in for the DC-6).