British lawyer and politician, distinguished for his military reforms before World War I. He was created a viscount in 1911.
Born and educated in Edinburgh, Haldane was called to the English bar in 1879 and became a queen's counsel in 1890. A Liberal MP from 1885 to 1911, Haldane achieved his most important work while he was secretary of war (1905–12). In 1907 he created the Territorial Force (later the Territorial Army), which facilitated the immediate dispatch of the British Expeditionary Force to France at the start of World War I. In 1909 he set up the Imperial General Staff, having visited Germany three years earlier to study the workings of the German general staff. As Anglo-German relations deteriorated, Haldane again visited Germany (1912) in a vain attempt to ease tensions. Appointed lord chancellor in 1912, he created additional lords of appeal to speed up the legal system, but was dismissed in 1915 for allegedly pro-German views. By the end of the war he had joined the Labour Party, and in 1924 Ramsay MacDonald appointed him again to the lord chancellorship. Haldane was also a philosopher, the author of The Reign of Relativity (1921). An associate of Sidney and Beatrice Webb, he helped found the London School of Economics in 1895.