He was the son of Sir John Charles Molteno, who at the time was Prime Minister of the Cape, and many of his relatives held positions of influence in business and government.

Soon after joining the Navy, he was discovered to be a lethally accurate shot, was selected for special training, and quickly distinguished as a gun specialist.

[5] He commanded several warships in World War I, including HMS Revenge, Antrim, King George V, Shannon, Minotaur, and Bellerophon.

Molteno fought at the Battle of Jutland, the largest naval engagement of the First World War, commanding from the armoured cruiser HMS Warrior.

[6] HMS Warrior was part of the ill-fated First Cruiser Squadron, which was deployed as a vanguard several miles ahead of the main British fleet.

With casualties mounting and signs of flooding, Molteno manoeuvred Warrior out of harm's way as the beleaguered HMS Warspite unintentionally drew the enemy fire.