1) This question was a little sneaky. The Dalmatian town of Curzola officially claims, with the support of a small minority of historians, to be the birthplace of Marco Polo. (Dalmatia was held by Venice at the time, so it's not implausible, but the theory seems a little too convenient for the Croatian tourism board.

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2) Helen Duncan, a Scottish charlatan and pretended medium, had a history of convictions for faking contact with the other world. However, in 1941, she announced that she had contacted a dead sailor from the recently sunk battleship HMS Barham. This was a slight problem, since the British High Admiralty completely suppressed the news of the Barham's sinking for two months after the event, for propaganda reasons. In 1944, Duncan was brought to trial on a somewhat trumped-up charge of witchcraft. (Under the 1735 Witchcraft Act, which replaced previous laws banning actual witchcraft, it became a crime to
pretend to be a witch.) This was done due to rather improbable fears that she might reveal details of the upcoming D-Day assault.
3) The massively influential English romantic William Wordsworth was most controversial in his day for his enthusiastic support of the French Revolution. "Europe at that time was thrilled with joy,/ France standing on the top of golden hours,/ And human nature seeming born again," he wrote. "Bliss was it in that dawn to be alive,/ But to be young was very Heaven!" As Bertrand Russell's formulation implies, Wordsworth later became a Tory and wrote reams of forgettable verse, his genius apparently exhausted. Like the former Canadian Prime Minister Brian Mulroney and Stevie Wonder, Wordsworth had no sense of smell.
4) Peyton Randolph was the first to preside at the Continental Congress, which he did for a month and a half in 1774.
5) The Terrace Mutiny occurred in 1944 on Canada's west coast, when a French Canadian unit revolted against its officers and seized weaponry. It was caused by rumours that conscripted soldiers were imminently to be sent overseas. This was not true, but conscription (and, in fact, military commitments of any kind) has always been explosively unpopular in Quebec. The Army regained control after five days.
6) Antoine de Saint-Exupéry, author of
Le Petit Prince, disappeared in 1944 while flying a reconnaissance mission in the Mediterranean. Perhaps more famous in the English-speaking world, Roald Dahl crashed his fighter plane in the Libyan desert in 1940, an event which he used in his first published work, a short story called "Shot Down Over Libya".
7) Sir Henry Campbell-Bannerman, PM 1905-1908, was the first First Lord of the Treasury on whom the title of Prime Minister was officially bestowed, though the term was used as early as Walpole's administration. He is also the only PM to have died while in residence at 10 Downing Street.
8) The central figure in this question is Ossian, a character in and the supposed author of a revolutionary epic published by the Scot James Macpherson in the second half of the 18th century. Macpherson claimed to be translating a 3rd-century Scottish epic from various documents and oral traditions. This claim was sharply questioned by some critics in his lifetime, and is now known to be problematic at best-- while it's certainly true that the Ossian poems were really translated from Scottish originals, their antiquity is unclear, and Macpherson creatively altered and redacted his source materials in order to suit contemporary tastes. In any event, there's no particular reason to credit Macpherson's notion of Ossian as a Scottish Homer, and we simply don't know whether there is a single poet responsible for the epic. Regardless, Ossian created a literary firestorm that endured until Byron's time, and many ranked him alongside Homer and Virgil.
Felix Mendelssohn-Bartholdy visited Scotland and wrote (among other things) the overture known as Fingal's Cave. Fingal was Macpherson's rendering of the Scottish version of the Irish hero Finn MacCool, and featured prominently in the epic as Ossian's king. Samuel Johnson was one of the leaders of the chorus denouncing Macpherson's epic as fraudulent. Goethe, like many other luminaries of his day, was infatuated with Ossian, and the hero of his The Sorrows of Young Werther likewise. (Werther was so iconic that his suicide at the end of the novel inspired dozens of young European men to off themselves.) The last picture is one of a series of riotous Ossian-related paintings executed by the French romantic Anne-Louis Girodet.
9) Geoffrey Chaucer (
chausseur). The short answers are: the siege of Rheims, Edward III, and Wat Tyler's 1381 Peasant Revolt. Chaucer lived in an apartment above the New Gate, through which Tyler's rebels marched into London. As I rather coyly said, Chaucer was an author (arguably second only to Shakespeare among English poets), best known in our time for his Canterbury Tales. His most significant textual influences were Ovid and Boethius, but luceafarul's answer of Boccaccio was equally acceptable, since Chaucer drew on Boccaccio for both the Tales and for his masterpiece
Troilus and Criseyde. Chaucer's allegorical poem
The House of Fame contains the first written reference to the Milky Way. (Incidentally, I've no idea what he did with a daily gallon of wine-- my imagination pictures him using some of it to water his rose bushes or something.)
10) Timothy the tortoise served as ship mascot aboard the HMS Queen, a ship-of-the-line that bombarded Sevastopol. She died in 2004.
11) When Magellan's ship
Victoria limped back to Spanish port after its circumnavigation of the globe, it was a Thursday on the ship and a Friday on land, since the voyage meant that the sailors had experienced one fewer rotation of the Earth than everybody else. This oddity, after careful verification of the ship's logs, demonstrated the need to have an International Date Line.
12) Martin Luther was a very peculiar man, and among his peculiarities was a tendency to constipation which caused him to spend a lot of his time in his privy. It goes, er, deeper than that, though, because he has these extremely coarse, er, passages in which he insists that Satan lives quite literally in human filth, or in which he describes having faeces-flinging fights with the devils he routinely saw. Get thee behind me, Satan, indeed.