Seizing and decoding the secret HVB codebook
The secret Handelsverkehrsbuch (HVB) codebook was seized from a German ship in Australia. The book's cipher was decoded to assist the British Royal Navy during World War I.
Capturing 'prizes' of war
Australia and other nations in the British Empire adopted a policy to seize enemy vessels in their ports at the start of the war. This prevented the ships from being used by the Imperial German Navy.
Most German merchant navy ships seized in Australian ports became prizes of war. They were put back into service as supply ships or troopships with Allied crews.
A German passenger steamer, SS Seydlitz, hurriedly left Sydney harbour on 4 August 1914. Britain had just declared war on Germany.
Australian naval authorities worried that Seydlitz's crew would warn incoming German vessels to turn back.
Deceiving the SS Hobart
A German-Australian Line cargo steamer, SS Hobart, left Fremantle on 4 August 1914. Bound for Melbourne, the captain was wary of international tensions but remained unaware that war had been declared. As part of the British Empire, Australia no longer offered safe harbours for German vessels.
The RAN wanted to prevent Hobart from receiving Seydlitz's warnings. It ordered wireless stations in southern Australia to jam signal traffic day and night. The plan succeeded.
SS Hobart steamed past Cape Otway on 11 August and stopped off Port Phillip Heads. The District Naval Officer, Captain John Tracy Richardson, boarded the ship as part of a navy team. The men were disguised as quarantine officials.
When safely in range of the land artillery batteries, Richardson took control of the ship, but still allowed the crew some freedom. Despite two searches by the Customs Department, the team found nothing of interest on board.
But that night, Richardson stayed in the captain's bunk and pretended to be asleep. Two of Hobart's crew stealthily opened the cabin door just before 4am and entered. When they opened a concealed panel under the desk, Richardson — with revolver and flashlight in hand — arrested the men.
A search revealed a hidden safe. Inside was a German Mercantile Code Book, or Handelsverkehrsbuch (HVB), and more importantly — its cipher key. The code was used to encrypt messages to and from Vice Admiral von Spee's deadly East Asiatic Squadron.
The Australian Government imprisoned the crew of the SS Hobart in an internment camp. The SS Hobart was requisitioned and readied for service as the transport, HMAT Barambah (A37).
Decoding the cipher
The RAN passed the two documents to Captain Frederick Wheatley in Melbourne.
Wheatley was a talented navy instructor, German linguist, mathematician and cryptographer. He successfully translated the book and worked out its cipher key.
His decryption had far-reaching benefits for the Allies. It might have given the Royal Navy the intelligence it needed to destroy von Spee's fleet in the South Atlantic.
Acting on the intelligence
Other documents seized on SS Hobart showed which neutral ports the German vessels should proceed to in the event of war. The instructions mentioned Chile.
Reports that German crews were buying maps for South America also indicated the possible location of the East Asiatic Squadron.
The analysis proved correct.
In November 1914, the Royal Navy suffered its worst defeat by the Germans in more than 100 years. In the Battle of Coronel, off the coast of Chile, the British lost:
- two battleships
- over 1600 sailors, including Rear Admiral Christopher Cradock
Britain had its revenge 5 weeks later. The Royal Navy defeated the German fleet in the Battle of the Falkland Islands, in which von Spee was killed.