Invasion literature (or the invasion novel) was a historical literary genre most notable between 1871 and the First World War (1914). The genre first became recognizable starting in England in 1871 with the short story The Battle of Dorking, a fictional account of an invasion of England by Germany. The Battle of Dorking was so popular it started a literary craze for stories that aroused imaginations and anxieties about hypothetical invasions by foreign powers, and by 1914 the genre had amassed a corpus of over 400 books, many best-sellers, and a world-wide audience. The genre was extremely influential in England in shaping politics, national policies and popular perceptions in the years leading up to the First World War, and still remains a part of popular culture to this day.

The Battle of Dorking (1871) by George Tomkyns Chesney first appeared in Blackwood's Magazine, a respected Victorian political journal read by important British politicians. The short story describes the invasion of England by an unnamed enemy (who happen to speak German) in which the narrator, and 1000 citizens, defend the small English town of Dorking, with no supplies or news of outside events. The story then moves forward in time 50 years and England is still devastated. The author, like many British at the time, was alarmed by Prussia's successful invasion of France in 1870, defeating Europe's largest army in only two months. The Battle of Dorking was initially meant to shock readers into becoming more aware of the possible dangers of a foreign threat, but unwittingly created a new literary genre appealing to popular anxieties. The story was an immediate success, with one reviewer saying "We do not know that we ever saw anything better in any magazine... it describes exactly what we all feel." It was so popular that the magazine was re-printed six times, a new pamphlet version was created, dozens of spoofs were created, and it was for sale throughout the British Empire. One running joke in England at the time was an injury, such as a bruise or scrape, was attributed to a wound received at the battle of Dorking.

Between the publication of The Battle of Dorking in 1871 and the start of First World War in 1914 there were hundreds of authors writing invasion literature, often topping the best seller lists in Germany, France, England and the United States. During the period it is estimated over 400 invasion works were published. Probably the best known work was H. G. Wells's The War of the Worlds (1898), a faithful reproduction of The Battle of Dorking but with a science fiction theme. Dracula (1897) also tapped into English fears of foreign forces arriving unopposed on its shores, although between 1870 and 1903 the majority of these works assumed that the enemy would be France, rather than Germany.

This changed with the publication of Erskine Childers's 1903 novel The Riddle of the Sands. Often called the first modern spy novel, two men on a sailing holiday thwart a German invasion of England when they discover a secret fleet of invasion barges assembling on the German coast. William Le Queux was the most prolific author of the genre; his first novel was The Great War in England in 1897 (1894) and he went on to publish from one to twelve novels a year until his death in 1927. His work was regularly serialised in newspapers, particularly the Daily Mail, and attracted many readers. It is believed Ian Fleming's James Bond character was inspired by Le Queux's agent "Duckworth Drew". Le Queux's most popular invasion novel was The Invasion of 1910 (1906) which was translated into twenty-seven languages selling more than a million copies world-wide. Le Queux and his publisher changed the ending depending on the language, so in the German print edition the fatherland wins, while in the English edition the Germans lose. Le Queux was said to be the Queen Alexandra's favorite author.

Invasion literature was not without detractors; policy experts in the years preceding the First World War said invasion literature risked inciting war between England and Germany and France. Critics such as Prime Minister Henry Campbell-Bannerman denounced Le Queux's The Invasion of 1910 as "calculated to inflame public opinion abroad and alarm the more ignorant public at home." Journalist Charles Lowe wrote in 1910: "Among all the causes contributing to the continuance of a state of bad blood between England and Germany perhaps the most potent is the baneful industry of those unscrupulous writers who are forever asserting that the Germans are only awaiting a fitting opportunity to attack us in our island home and burst us up."

Stories of a planned German invasion rose to increasing political prominence from 1906. Taking their inspiration from the stories of Le Queux and Childers, hundreds of ordinary citizens began to notice foreigners behaving suspiciously. This trend was accentuated by Le Queux, who collected 'sightings' brought to his attention by readers and raised them through his association with the Daily Mail. Subsequent research has since shown that no significant German espionage network existed in Britain at this time. Claims about the scale of German invasion preparations grew increasingly ambitious. The number of German spies was put at between 60,000 and 300,000 (in spite of the total German community in Britain being no more than 44,000 people). It was alleged that thousands of rifles were being stockpiled by German spies, to arm saboteurs at the outbreak of war.

Calls for government action grew ever more intense, and in 1909 it was given as the reason for the secret foundation of the Secret Service Bureau, the forerunner of MI5 and MI6. Historians today debate whether this was in fact the real reason, but in any case the concerns raised in invasion literature came to define the early duties of the Bureau's Home Section. Vernon Kell, the section head, remained obsessed with the location of these saboteurs, focusing his operational plans both before and during the war on defeating the saboteurs imagined by Le Queux.

The invasion genre has persisted to this day in popular culture because it continues to appeal to the anxieties of the moment. Current invasion scenarios include terrorism, pandemics, and ecological and environmental catastrophe. After the Second World War fears of Communist invasion became pronounced in films like Invasion of the Body Snatchers (1956), and more explicitly in the 1980s with Red Dawn and Amerika. American TV and movies in the period following the 9/11 terrorist attacks had a notable number of new "alien invasion" themed shows.

Although the invasion literature genre became most notable with The Battle of Dorking, there was a mini-boom of invasion stories appearing in France in the 1780s soon after the French first developed the hot-air balloon. Poems and plays depicting armies of balloons headed to England could be found in France and even America. However it was not until the Prussians first used advanced technologies such as breech-loading artillery and railroads to defeat the French in 1870 that the imagined fears of invasion by a technologically superior enemy became real.

A main theme in invasion literature is a fear of and fascination with technology. The invasions are made possible by a technological leap that gives the invader a supra-human advantage.

I.F. Clarke, a British literary scholar, is recognized as the primary expert on the genre.

• The Battle of Dorking (1871), George Tomkyns Chesney
• The Great War in England in 1897 (1894), William Le Queux
• The War of the Worlds (1898), H. G. Wells
• The Riddle of the Sands (1903), Erskine Childers
• The Invasion of 1910 (1906), William Le Queux
• Spies of the Kaiser (1909), William Le Queux

• Alien invasion
• Alternate history (fiction)

• I.F. Clarke, 1997. "Future War Fiction". An award-winning essay.
• I.F. Clarke, 1997. "Before and After The Battle of Dorking".

• Andrew, Christopher, 1985. Secret Service: the making of the British intelligence community. ISBN 0434021105
• I.F. Clarke, 1966/1992. Voices Prophesying War: Future Wars, 1763-3749. ISBN 0192123025
• Tom Reiss, 2005. Imagining the Worst: How a literary genre anticipated the modern world. The New Yorker, November 28, 2005. pp.106-114