[7][8] Knut Hammarskjöld was a noble, landowner and female line descendant of an illegitimate daughter of Eric XIV of Sweden.

[citation needed] Hjalmar's younger brother Carl Gustaf Hammarskjöld later became Sweden's minister of defence.

[11][12] Agnes was the daughter of director general Gustaf Fridolf Almquist [sv] and his wife Maria Vilhelmina Gradin.

[5] In this position, he made an ambitious but unsuccessful attempt to resolve the problems concerning the right to vote, and was, on his resignation, appointed president of the Göta Court of Appeal.

Hammarskjöld resisted making concessions to the Norwegians, and they regarded him as the person most responsible for their failure to attain more favorable conditions for the dissolution.

[14] The working relationship between the Swedish delegates was good, and Hammarskjöld was specifically pleased with his cooperation with the Liberal politician Karl Staaff.

[5] In 1905, after Lundenerg's government ended, Staaff became prime minister, and he appointed Hammarskjöld to be the Swedish ambassador to Copenhagen in December of that year.

Hammarskjöld was sent back to Copenhagen to negotiate in 1912, specifically disagreements over territorial waters, pilot and navigational rules, and the expectations of neutral countries during wartime.

After the outbreak of the First World War that same year, a truce was established between the parties and the defense problem was solved to the satisfaction of the military.

It was during this time that the term 'Hunger shield' (Swedish: Hungerskjöld) was coined, because his intractability impeded efforts to get necessary food exports into Sweden.

[20] Hammarskjöld had a dominant nature and was perceived by his opponents as authoritarian and strong-willed, but claims that he favoured Germany lack documented support.

[5] He was voted into the Swedish Academy in 1918[4][21] to the same chair as Prime Minister Louis De Geer had occupied,[citation needed] number 17.

Hjalmar Hammarskjöld died on 12 October 1953 in Stockholm,[23] just over six months after his youngest son became the second Secretary General of the United Nations.