In February 1915, Arcadian was hired by the Admiralty.
On 7 April 1915 at Alexandria, General Sir Ian Hamilton came aboard and used Arcadian, together with the battleship Queen Elizabeth, as his headquarters ship during the opening phase of the Gallipoli Campaign.
Once Hamilton's staff had transferred to a shore base at Imbros, Arcadian was employed as a troop ship in the Mediterranean.

On 15 April 1917 Arcadian was en route from Thessaloniki (Salonika) to Alexandria with a company of 1,335 troops and crew and escorted by a Japanese Navy destroyer.
Shortly after completing a boat drill, while 26 miles north east of the Greek island of Milos, Arcadian was hit by a single torpedo from the German submarine SM UC-74 and sank within six minutes with the loss of 279 lives.
A contemporary newspaper article described how four of Arcadian's overcrowded lifeboats were successfully lowered before she sank.
Some of the dead were cooks and stokers who were working below decks.
The escorting destroyer had two torpedoes launched at her while she was attempting to rescue men from the water; survivors reported that she had lowered three of her own boats while going "at full speed".
More survivors, who had been clinging to a raft, were rescued at midnight by the Q-ship HMS Redbreast.
Among the dead was the eminent bacteriologist, Sir Marc Armand Ruffer, who was returning to Alexandria after advising on the control of an epidemic among troops based at Thessaloniki.
In February 1915, Arcadian was hired by the Admiralty. On 7 April 1915 at Alexandria, General Sir Ian Hamilton came aboard and used Arcadian, together with the battleship Queen Elizabeth, as his headquarters ship during the opening phase of the Gallipoli Campaign. Once Hamilton's staff had transferred to a shore base at Imbros, Arcadian was employed as a troop ship in the Mediterranean.
On 15 April 1917 Arcadian was en route from Thessaloniki (Salonika) to Alexandria with a company of 1,335 troops and crew and escorted by a Japanese Navy destroyer. Shortly after completing a boat drill, while 26 miles north east of the Greek island of Milos, Arcadian was hit by a single torpedo from the German submarine SM UC-74 and sank within six minutes with the loss of 279 lives. A contemporary newspaper article described how four of Arcadian's overcrowded lifeboats were successfully lowered before she sank. Some of the dead were cooks and stokers who were working below decks. The escorting destroyer had two torpedoes launched at her while she was attempting to rescue men from the water; survivors reported that she had lowered three of her own boats while going "at full speed". More survivors, who had been clinging to a raft, were rescued at midnight by the Q-ship HMS Redbreast. Among the dead was the eminent bacteriologist, Sir Marc Armand Ruffer, who was returning to Alexandria after advising on the control of an epidemic among troops based at Thessaloniki.
SS Arcadian