His father (Sir John MacLeod) was a successful businessman before entering politics as a Unionist MP; his mother Edith was from a wealthy Lancastrian family (owning cotton mills).

Upon the outbreak of the First World War, and having been a cadet in the Officers Training Corps, MacLeod was commissioned in the Argyll and Sutherland Highlanders, British Army, as a temporary second lieutenant on 19 September 1914.

He was awarded the Military Cross (MC) in October 1917,[4] and the French Croix de Guerre with palm for bravery in 1918.

He carried out his duties as adjutant as well, and was of the greatest assistance in keeping cohesion.His experience of this total war profoundly affected MacLeod, leading him to train for the ministry.

His wartime experiences, combined with a profound disillusionment by post-World War I political rhetoric of "a land fit for heroes," deeply affected him.

Confronted by the realities of the depression and unemployment faced by those less privileged than he, MacLeod gradually moved towards supporting socialism and pacifism.

He resigned (giving up the financial security of a parish minister's stipend) to become the full-time leader of the Iona Community, which he founded in 1938.

[9][10] As a result, for the first time in human history, a World Constituent Assembly convened to draft and adopt the Constitution for the Federation of Earth.

[11] During World War II, he served as locum minister at Canongate Kirk in Edinburgh—a parish also then afflicted by poverty.

He was invited by the congregation to return to Govan Old Parish Church in 1948, but the Presbytery of Glasgow refused to approve his appointment, given his wish to continue his active leadership of the Iona Community.

Despite a feeling of hurt and rejection over the "Govan Case", MacLeod remained one of the highest-profile figures in the Church of Scotland.

[17] Although dismissed by some as a maverick, he helped to raise awareness of pacificism, ecumenism and social justice issues, and inspired many to become involved with such questions.