Smuts, Jan Christiaan (1870–1950), a South African statesman and army officer. He was prime minister of the Union of South Africa (1919–24 and 1939–48) and a leader in the British Empire. He helped to organize both the League of Nations and the United Nations.

Smuts was born in Cape Colony, of Dutch descent. After studying at Cambridge University in England, he practiced law for several years, first in Cape Colony and then in the Transvaal republic. In 1899 he joined the Boer army in the war against Great Britain. He was commander of the Boer guerrilla forces in Cape Colony, 1901–02.

After the Boer countries had been annexed by victorious Great Britain, Smuts recognized the need for cooperation between the Dutch and British. He was influential in forming the Union of South Africa in 1910 and held several posts in the first government, under Prime Minister Louis Botha. During World War I, Smuts, with General Botha, commanded forces that conquered German South-West Africa (Namibia) in 1915. Smuts later commanded forces in East Africa.

Smuts represented South Africa in the Imperial War Cabinet at London, 1917–18, and was a delegate to the Versailles Peace Conference in 1919. He was active in the founding of the League of Nations.

Upon Botha's death in 1919 Smuts became prime minister. He continued to encourage cooperation between the Boers and the British. In 1924 he was replaced by James Hertzog, who advocated separation from Britain. Smuts again became prime minister in 1939 when Hertzog, who opposed entering World War II, resigned. During the war, Smuts served as commander of the Union's armed forces. As a delegate to the United Nations conference at San Francisco (1945), he helped to write the preamble to the UN charter. After his party was defeated in the elections of 1948, Smuts retired from public life.