Terry Pratchett - Jingo

In the latter part of the 19th century, the phrase “gunboat diplomacy” was coined to describe this British method of negotiating with uppity colonials. The gunboat in question would not normally be expected to do anything, merely to “show the flag” as a reminder that, however vulnerable it might appear on land, Britannia still Ruled the Waves, and could make life very difficult for anyone who got too obstreperous.

The Mary-Jane is a reference to Henry VIII's flagship, the Mary Rose , which (most embarrassingly) sank, in calm seas, immediately after being launched from Portsmouth in 1545. The ship was recovered in the 1980s, and is now a tourist attraction.

Theodore Roosevelt famously summarised his foreign policy as “Speak softly, and carry a big stick.”

This echoes a famous line from Stanley Kubrick's 1964 movie Dr Strangelove , which has President Merkin Muffley (Peter Sellers) saying: “Gentlemen, you can't fight in here! This is the War Room.”

A character in Dickens' Oliver Twist is called the Artful Dodger.

Carrot has formed Ankh-Morpork's first scout troop. This salute parodies the traditional (but now discontinued) Cub Scout exchange “Dyb dyb dyb.” “Dob dob dob.”. The ‘dyb’ in the challenge supposedly stands for “do your best”, the ‘dob’ in the scouts' response for “do our best”.

This sounds very much like the story of young Tom the chimney sweep's transformation, told in moralistic Victorian children's tale The Water Babies , written in 1863 by Charles Kingsley.

Press-ganging was the 18th-century equivalent of conscription. A ship's captain, finding himself short-handed while in a home port, would send a gang of his men round the port, enlisting anyone they could find who looked like a sailor. Often this involved simply picking up drunks, but it was not unheard-of for men to be taken by force.

In Arabic, “al” is the definite article, and it is joined to the word that it defines.

The idea of treating zero as a number was one of several major contributions that Western mathematics adopted from the Arabs.

A long-running series of British commercials for a certain brand of bread emphasised the Yorkshire origins of the manufacturer. This slogan is in a parody of a Yorkshire accent, presumably for similar reasons.

Reg Shoe first appeared in Reaper Man as the founder of the Campaign for Dead Rights (slogans included “Undead, yes! Unperson, no!”). Possibly Vimes has forgotten that he personally ordered zombies to be recruited into the Watch, towards the end of Feet of Clay .

Swires was the name of the gnome Rincewind and Twoflower encountered in The Light Fantastic . Given that gnome lives are described in that book as ‘nasty, brutish and short’, it seems unlikely that this is the same gnome. Possibly a relative, though.

A popular song from the Second World War had the lyric:

The phrase was also used as the title of a stage play (filmed in 1960) by Willis Hall, describing the plight and fate of a squad of British soldiers in Burma.

In the Good Old Days™, besieging armies would sometimes hurl the rotting corpses of dead animals over the city walls by catapult, with the aim of spreading disease and making the city uninhabitable. So in a sense, a dead dog could be a siege weapon…

Leshp bears a resemblance to H. P. Lovecraft's similarly strange-sounding creation, R'lyeh — an ancient, now submerged island in the Pacific, inhabited by alien Things with strange architecture, which rises at very long intervals and sends people mad all over the world. For full details, see Lovecraft's The Call of Cthulhu .

“It'll all be over by Christmas” was said of the First World War by armchair strategists, in August 1914. Ironically, the phrase has become a popular reassurance: more recently, President Clinton promised the American public in 1996 that US troops in Bosnia would be “home for Christmas”.

Ahmed's catchphrase is borrowed from Signior So-So, a comic Italian character in the famous wartime radio series It's That Man Again (ITMA).

The original Fanny Adams was an eight-year-old girl in Alton, Hampshire, whose dismembered body was discovered in 1867. About the same time, tinned mutton was first introduced in the Royal Navy, and the sailors — not noted for their sensitivity — took to calling the (rather disgusting) meat “Sweet Fanny Adams”. Hence the term came to mean something worthless, and finally to mean “nothing at all”.

Oxford University has a ceremony called the Encaenia, which also involves lots of old men in silly costumes and a procession ending in the Sheldonian Theatre.

The Pavlovian experiment in our world involved ringing a bell before and during the feeding of a group of dogs. After a while the dogs learned to associate the ringing of the bell with food. A part of them was essentially programmed to think that the bell was the same thing as food.

Refers to the fact that, for many years, surgeons used to double as barbers, or vice versa.

The Keystone Cops were a squad of frantically bumbling comedy policemen from the silent movie era.

The “lone gunman” theory is still the official explanation of John F. Kennedy's assassination, despite four decades of frenzied speculation. Conspiracy theorists like to claim that Someone, Somewhere is covering up the truth, in much the same way as Vimes and Vetinari are conspiring to cover it up here.

In 1363, in England, Edward III — then in the early stages of the Hundred Years' War with France — ordered that all men should practise archery on Sundays and holidays; this law remained technically in force for some time after the longbow was effectively obsolete as a weapon of war.

In our world, an early attempt at an internal combustion engine used pellets of gunpowder, stuck to a strip of paper (rather like the roll of caps for a cap pistol). I understand that the attempt was just as successful as Leonard's.

Burnt umber is a dark, cool-toned brown colour. Umber is an earth pigment containing manganese and iron oxides, used in paints, pastels and pencils. The name comes from Umbria, the region where it was originally mined and adopted as a pigment for art.

The live film of JFK's assassination, allegedly, shows similar inconsistencies with the official account.

The official account of JFK's assassination describes how a bullet moved in some very strange ways through his body. Conspiracy theorists disparage this as the “magic bullet theory”.

In our world there is a magazine Guns And Ammo; this appears to be the Discworld equivalent.