In August 1914, the ship was requisitioned for military service.
Berrima was taken to
Cockatoo Island Dockyard on 12 August for refitting, but instead of being converted into a troop transport as originally planned, the ship underwent a six-day conversion for naval service. The modifications included converting holds into accommodation for 1,500 officers and soldiers, establishing a hospital was on the upper deck, and fitting four BL naval guns and magazines, two on the
forecastle, two on the
poop deck. On 17 August, the ship was commissioned as the auxiliary cruiser HMAS
Berrima, under the command of Commander J.B. Stevenson. The ship's civilian officer complement were inducted into the
Royal Australian Naval Reserve, and the crew was supplemented by
Royal Navy and RAN sailors.
Berrima left Sydney on 19 August 1914 carrying men of the
Australian Naval and Military Expeditionary Force, consisting of a battalion of 1,000 infantry and a small battalion of 500 RAN Reservists and time-expired Royal Navy personnel, for operations against the
German New Guinea colonies.
Berrima met the naval units of the expeditionary force off
Rossel Island on 9 September. Troops were landed at
Herbertshöhe and
Rabaul on 11 and 12 September respectively, and on the
New Guinea mainland near
Madang on 24 September. The ship was retroactively awarded the
battle honour "Rabaul 1914" in March 2010 to recognise these landings.
Berrima subsequently returned to Sydney and, despite plans to employ her as an
armed merchant cruiser, was
paid off on 20 October 1914. She was converted to a troop transport in November 1914. In her new role, His Majesty's Australian Troop Transport (HMATT)
Berrima sailed for the Middle East in December 1914 as part of the second troop convoy, carrying Australian and New Zealand troops and towing the submarine
AE2.
Berrima continued to work under the liner requisition scheme until 18 February 1917, when she was torpedoed in the
English Channel off
Portland with the loss of four lives. After the rest of the crew were evacuated by the
destroyer , then towed into Portland Harbour, beached (due to the lack of drydock facilities), and repaired. The Commonwealth relinquished control on 10 October 1917. After being repaired she was requisitioned by the Shipping Controller for use as the Atlantic stores and munitions ferry service. ==Post-war career and fate==