Robert Coleman, born in Australia, came to Europe to fight in World War I, where he was commissioned as a second lieutenant in the 5th (Territorial Force) Battalion, Essex Regiment, on December 15, 1914. Then, he served in France from November 1915. He was seconded to the 63rd Battalion, Machine Gun Corps, on April 23, 1916, and promoted to lieutenant on August 19, 1917.

Coleman was awarded the Military Cross on April 2, 1919, for his gallantry and initiative east of the Canal de l'Escaut on September 30, 1918. His citation highlighted his skillful handling of his section to neutralize enemy machine guns, which allowed the infantry to advance.

Coleman married Constance Irene Machin on August 23, 1915.
After the First World War, he was a crew member on Cyril Wright’s 1920 yacht Ancora from the Royal Burnham Yacht Club, and won a team Gold Olympic medal.