Between Zeppelins and U-boats: A Captain, a Cruiser, and the North Sea

Steel and shadow stalked the North Sea as HMAS Sydney operated in the First World War’s most pivotal and dangerous maritime theatre, a contested zone shaped by the British naval blockade of Germany. Here, the cruiser was hunted by German U-boats (short for Unterseeboote or "undersea boats”) below the surface and zeppelins (long-range airships used for reconnaissance and bombing raids) above.

Sydney’s service in the North Sea has long stood in the shadow of its earlier triumph, the defeat of the German cruiser SMS Emden off the Cocos Islands in November 1914, a victory widely regarded as Australia’s first major naval success in the war.

Born in 1873 in Rose Bay, Sydney, John Saumarez Dumaresq was the son of pastoralist William Alexander Dumaresq and his English-born wife, Edith Helen, née Gladstone. He came from a well-established colonial family and despite spending much of his youth and naval career in England, he retained strong ties with Australia.

It was perhaps fitting, then, that Dumaresq, was appointed to command HMAS Sydney in February 1917, a vessel named after the city of his birth.

He was one of many Royal Navy officers assigned to Australian vessels during the war, due to the Royal Australian Navy’s inexperience and its need for experienced leadership, professionalism, and operational expertise.

Dumaresq was also considered one of the Royal Navy’s most innovative officers and took a keen interest in the science of naval warfare.

He was described by the Official Historian of the Navy Arthur Wilberforce Jose as “a man of exceptional ability and vivid imagination”.

These qualities would be put to the test in 1917, when German naval zeppelins began menacing British ships in the North Sea.

On 3 May 1917, Sydney departed Rosyth, a major British naval base on Scotland’s east coast and the headquarters of the battle cruiser squadrons, accompanied by the light cruiser HMS Dublin and four destroyers to conduct an anti-submarine sweep of the Forth and Humber estuaries—key maritime approaches to Britain’s industrial ports and shipping routes.

By the morning of 4 May, the sweep was complete, and Sydney turned north-north-west to return to base.

At 10.30, the ship’s leading signalman, John William Seabrook, responsible for relaying communications between ships, wrote in his diary (held in the Memorial’s Private Records collection): “Sydney sighted a Zeppelin. Opened fire and made a signal to all ships to “Engage Zeppelin.”

Sydney and Dublin led the pursuit of the airship, opening fire at an extreme range.

HMS Obdurate, one of the four escorting destroyers, was ambushed by German U-boats and dropped depth charges (explosive devices designed to detonate underwater against submerged submarines) before proceeding to independently pursue the zeppelin.

At 10.54, the cruisers came under attack. Dublin observed a torpedo passing ahead and sighted two submarines nearby. Recognising that the zeppelin was luring his squadron into a trap, Dumaresq ordered his ships to disperse.

The cruisers maintained course while the destroyers attempted to get behind the airship.

Over the next few hours, the zeppelin stalked the British ships. Seabrook recorded, “Sydney fired all her anti-aircraft ammunition and the Zepp let go all her bombs. Neither hit the other.”

By 1 pm, the encounter had ended, with no casualties on either side.

Sydney’s captain, Dumaresq, had advocated for the installation of aircraft launching platforms on ships since the 1916 battle between the Royal Navy and the German High Seas Fleet at Jutland.

The encounter with the German zeppelin, which demonstrated the growing threat from the air and the limitations of ship-based guns alone, prompted the Admiralty to adopt Dumaresq’s vision, as recognised in the First World War Official History.

During a later refit, Sydney became the first cruiser to be fitted with an aircraft launching platform, with successful trials beginning on 8 December 1917.

Sydney’s aircraft later proved effective against German naval air power.

On 1 June 1918, during a raid on enemy minesweepers in Heligoland Bight, an aircraft launched from Sydney intercepted German reconnaissance aircraft, destroying one and driving off another.

The service of HMAS Sydney in the North Sea, with Dumaresq’s innovations, contributed to reducing the threat posed by German air power in one of the most important operational areas of the First World War.

Further sources:

Peter Firkins, John Saumarez Dumaresq (1873–1922). Australian Dictionary of Biography

First World War Official Histories, Volume IX, The Royal Australian Navy, 1914–1918 (9th edition, 1941), Chapter X, Service in European Waters

[Official History, 1914-18 War: Naval records of Arthur W Jose:] Home Station, 1917-4 May 1917, action with Zeppelin [airship], AWM36, BUNDLE 29/39

[Official History, 1914-18 War: Naval records of Arthur W Jose:] Home Station miscellaneous, Flying off decks of Battle Cruisers and Light Cruisers (HMAS SYDNEY) [aircraft], AWM36, BUNDLE 31/10

https://www.awm.gov.au/collection/P163

Seabrook, John William (Leading Signalman, HMAS Sydney), 1DRL/0669