Dag Hammarskjöld was born in Jönköping, although he lived most of his childhood in Uppsala. He was the fourth and youngest son of Hjalmar Hammarskjöld, Prime Minister of Sweden, and Agnes Almquist. He studied at Uppsala University where he graduated with a Master's degree in political economy and a Bachelor of Law degree. He then moved to Stockholm.
From 1930 to 1934, he was a secretary of a governmental committee on unemployment. He also wrote his economics thesis Konjunkturspridningen (The Spread of the Business Cycle) and received his Doctorate from Stockholm University in 1933. In 1936, Hammarskjöld became a secretary in the Bank of Sweden and soon he was an undersecretary of finance. From 1941 to 1948, he served as a chairman of the Bank of Sweden.
Early in 1945, he was appointed as adviser to the cabinet on financial and economic problems, and coordinated government plans to alleviate the economic problems of the post-war period.
In 1947, Hammarskjöld was appointed to Sweden’s Ministry for Foreign Affairs, and in 1949 he became the State Secretary for Foreign Affairs.
In 1953-58 he was Secretary General of the United Nations. For the next eight years he worked tirelessly for world peace. His particular emphasis was on easing Cold War tensions betveen the United States and Russia.
The major crisis during his two terms was the Suez controversy (1956), in which he opposed Britain, France and Israel. His attempts to solve the problem of Congo (now Zaire), where he was killed in a plane crash while on a peace-keeping mission in Africa (1961), were attacked by the Soviet Union. He was posthumously awarded the Nobel Peace Prize for 1961.
In addition to world government, Hammarskjöld was interested in literature and philosophy. Here is a quote from the posthumously-printed Markings (which refers to his love for a man), his book of poetry and prose:
"You are your own god - and are surprised
when you find that the wolf pack is hunting you
across the desolate ice fields of winter."
Hammarskjold was not openly gay during his lifetime. Given the climate in which he worked, public knowledge of his sexual orientation would likely have reduced his effectiveness.