The Battle of Hastings took place on the 14th of October 1066... this blogpost by historian Marc Morris talks about the common assumption that Harold Godwinson was killed by an arrow in the eye.

Punkie Night is celebrated in some communities in the Westcountry of England on the last Thursday in October. The tradition is thought to date back to when wives would haul their drunken husbands back from Chiselborough fair, using punkie lanterns - hollowed out mangelwurzels used to ward off evil spirits - as their guide. Later, children joined in the festivities and would go door to door asking for candles, with the implicit threat of pranks for households that did comply.
This is one, but definitely not the only, precursor to modern Halloween trick-or-treating.
Image: Punkie Lanterns, Dalwood, 1963

Collection of Halloween things 🎃

https://www.tg-me.com/historicalchan/3822

Pope Night (Boston, US, 1768).
This was an evolution of the British Guy Fawkes Night, held on the 5th of November. It became a generally anti-Catholic and anti-authority celebration, with effigies of the Pope frequently burnt. It often devolved into violence. After American independence, the celebration continued only in small towns.

(Yes this photo was later used, mistakenly unattributed, on the cover of a Beirut album)

8 November 1923: Imitating Mussolini's March on Rome, an alliance of nationalist groups called the Kampfbund surround the Bürgerbräukeller beer hall in Munich, Germany. Marching in, leader Adolf Hitler is unable to make himself heard and fires a pistol in the air, declaring that the revolution has begun. The intention is to seize control of the Bavarian government and march on the national Weimar government.

9 November 1923: the coup falters even as SA men seem to have taken over parts of Munich. Three crucial government hostages are released in the night by Ludendorff.
Despite taking over key government buildings, there is a lack of direction in what the plotters are trying to do. It is clear by morning that the police and army remain loyal to the state.

Vacillating and sleep-deprived, Ludendorff declares "we march!" and the plotters set off to the city centre. They meet soldiers of the German army there. Someone fires first, and in the chaos 16 Kampfbund, 4 soldiers, and a civilian are killed. Notably, Hermann Göring narrowly escapes death. Hitler flees to the countryside.

Armistice Day in Liverpool, UK, 1921. 1921 saw the introduction of the poppy as a symbol of the commemorations.
But globally, away from the pomp and decorum, there was considerable unrest in some places. In Liverpool itself, veterans disrupted the Silence because they were unhappy with how they had been treated by the government. In London, the same happened at the Cenotaph, and other demonstrations were reported across Europe. 'The dead are remembered but we are forgotten' was one phrase held on placards. It was clear the 1920s was not going to be an easy decade.
Source