The Broken Hill Proprietary Company Limited's ("BHP") ownership of shipping commenced late in 1917, following several years of chartering and nominee-participation. Success of the mining origins, in the west of New South Wales during the mid-1880s - the Company was incorporated in Melbourne in August 1885 - and the Port Pirie smelting operations and Newcastle coal linkages established by the turn of the century all contributed to the perceived shipping need and it was a natural progression.

Chartering and ownership of variously-named ships preceded the 1920 commencement in service (under fresh names) of the first of BHP's "Iron-named" ships, Iron Baron and Iron Prince, though Interstate Steamships Limited's Iron Monarch had been serving BHP from slightly earlier. The period to the late 1930s included difficult economic times for the nation and during that stage Australian Iron & Steel Limited became a BHP subsidiary.

As the Second World War opened, the Company had eight ships in service , while two "new-builds" joined these as the war progressed:-

From early in the war, the ships were strengthened to various levels, to bear gun platforms, to carry naval ("D.E.M.S.") gunners, to have anti-mine paravane booms fitted to the bows and to carry extra rafts and emergency supply and rescue equipment. Lives were saved later as a result and further defensive improvements occurred as the war progressed.

Two BHP ships were lost to enemy action, both "close to home". Iron Chieftain, en route Newcastle-Whyalla at night on 3 June 1942, was torpedoed and sunk east of Sydney by Japanese submarine I.24. Her Master and Chief Engineer were among the twelve crew lost. The thirty-seven survivors were rescued from a raft by HMAS Bingera and from a lifeboat washed onto The Entrance beach. Early February 1943 found a ten-merchant ship escorted convoy (OC 8) en route Melbourne-Newcastle, with Iron Knight, fully laden with iron ore, the leading vessel. Off Eden on 7 February, she fell victim to Japanese submarine I.21. Torpedoed and sinking immediately, the crew loss totalled thirty-six, including the Master. Fourteen survivors were taken, from a raft, to Sydney.

The company Interstate Steamships Pty. Limited had worked in close association with BHP for many years. At 1941 it owned two ships: Iron Crown (built 1922, 3353 gt, in service 1923-1942) and Echunga (built 1922, 3362gt, in service 1925-1957). BHP's important wartime activities were indirectly impacted by the loss, laden with iron ore, of Iron Crown on 4 June 1942. Torpedoed by Japanese submarine I.27 off Cape Howe, Victoria, she went down, with thirty eight of her forty two crew lost.

There were other shipping losses which, while not of their own vessels, impacted directly on BHP's specialist maritime operations: on 12 June 1942, off Sydney, the Panamian ship Guatemala, bound from Newcastle to Whyalla carrying coke and on 11 April 1943, off Lord Howe Island, the Yugoslav Recina bound Whyalla-Newcastle carrying ironstone. Both torpedoed, they were among a number of ships made available to Australia by the British Ministry of War Transport, as a result of greater access to charterings following the 1941 Mediterranean campaigns.

Through the improving counter-offensive years of the war, BHP's fleet, though not always without industrial difficulties, sustained its service to the nation's major heavy industries sector, Australia's platform for post-war re-building and the Company's threshold for its new era's ships.