Danger! And Other Stories (1918) was a collection of short stories published by Sir Arthur Conan Doyle.

The collection's title story, "Danger!", was written eighteen months before the outbreak of World War I

World War I

World War I , which was predominantly called the World War or the Great War from its occurrence until 1939, and the First World War or World War I thereafter, was a major war centred in Europe that began on 28 July 1914 and lasted until 11 November 1918...

. First published in the Strand Magazine

Strand Magazine

The Strand Magazine was a monthly magazine composed of fictional stories and factual articles founded by George Newnes. It was first published in the United Kingdom from January 1891 to March 1950 running to 711 issues, though the first issue was on sale well before Christmas 1890.Its immediate...

in July 1914, it was based on an imaginary country in Europe fighting Britain and intended to direct public attention to the great danger (submarines) which threatened the country. The story describes how Britain is in need of getting up to date in its naval preparations. A small country in Europe (Norland) has been fighting England, and is now invaded by an English army. However the small country has a naval flotilla of submarines under Captain John Sirius. Sirius uses his submarines to lay a naval blockade around the British Isles, so that no supplies can be landed. The result is that the British start suffering famine. However some of the submarines are sunk. The British are congratulating themselves, when Sirius, waiting outside of Liverpool, purposely torpedoes a large White Star liner. The British end up surrendering.

At the time there were plenty of popular writings about England facing Germany in an upcoming war. The best remembered are The Riddle of the Sands

The Riddle of the Sands

The Riddle of the Sands: A Record of Secret Service is a 1903 novel by Erskine Childers. It is an early example of the espionage novel, with a strong underlying theme of militarism...

by Erskine Childers

Robert Erskine Childers

Robert Erskine Childers DSC , universally known as Erskine Childers, was the author of the influential novel Riddle of the Sands and an Irish nationalist who smuggled guns to Ireland in his sailing yacht Asgard. He was executed by the authorities of the nascent Irish Free State during the Irish...

, and When William Came

When William Came

When William Came: A Story of London Under the Hohenzollerns is a novel written by British author Saki and published in 1913. It was set several years in what was then the future, after a war between Germany and Great Britain, which Germany won...

by "Saki". Doyle's story is another example of this genre of invasion literature

Invasion literature

Invasion literature was a historical literary genre most notable between 1871 and the First World War . The genre first became recognizable starting in Britain in 1871 with The Battle of Dorking, a fictional account of an invasion of England by Germany...

. Ironically, its conclusion was to mirror the fate of the Cunard liner Lusitania

Lusitania

Lusitania or Hispania Lusitania was an ancient Roman province including approximately all of modern Portugal south of the Douro river and part of modern Spain . It was named after the Lusitani or Lusitanian people...

two years later.