
15 years of TV shows, podcasts, online videos, social media posts, live events, books, articles and random conversations has convinced me of the power of anniversary.
People who would not otherwise give any thought to the sinking of the Titanic, or the assassination of Archduke Franz Ferdinand suddenly become fascinated by them if you tell them that it occurred precisely 100 years before.
History lovers, by contrast, find them equally interesting on the other 364 days of the year, perhaps we don’t need that more obvious connection to engage with the past.
What happened on your birthday?
It is not entirely surprising. Children, and a frankly disturbing number of adults, are obsessed with the day on which they were born.
This day, on which we celebrate or bemoan another completed trip around the sun, is a time when we pause to reflect on the passing of time, even though there is nothing different about that day to any others.

Image Attribution: Birthdays give our own personal anniversary, but it is fascinating to know what else may have happened on the day we were born.
For the fallen
As a society we choose to remember the fallen on a particular day, Armistice Day, the anniversary of the guns falling silent on the Western Front. On that important day we collectively remember those who have died on our behalf and those who live with often complex requirements as a result of their wartime service.
How politics frames history
Anniversaries matter. Alex Salmond managed to position the Scottish independence referendum as near as possible to the 700th anniversary of the Battle of Bannockburn, the crushing Scottish victory over the English army of Edward II.

Slobodan Milosevic delivered an inflammatory speech on 15 June 1989, the anniversary of both the battle of Kosovo, in which the Serbs fought the Ottoman Turks to a bloody stalemate in 1389, and the assassination of Franz Ferdinand by a Serb nationalist in 1914. Milosevic’s speech is seen as an important waypoint in the descent of the former Yugoslavia into war.
The centenary of the Battle of Leipzig was turned into a giant celebration of the Germany military might by the Kaiser’s government in 1913. Politicians use anniversaries as a way of recruiting the past, and sending it into battle in the present.

1. The Romulus and Remus story is a myth

2. By the fourth century BC, the story was accepted by Romans who were proud of their warrior founder

3. The new city’s first conflict was with the Sabine people

4. From the start Rome had an organised military
Regiments of 3,000 infantry and 300 cavalry were called legions and their foundation was ascribed to Romulus himself.5. Almost the only source on this period of Roman history is Titus Livius or Livy (59 BC – 17 AD)

6. Tradition has it that Rome had seven kings before it became a republic

7. After victory in the Latin War, Rome granted citizens’ rights, short of voting, to its conquered foes
This model for integrating vanquished peoples was followed for most of Roman history.8. Victory in the Pyrrhic War in 275 BC made Rome dominant in Italy
9. In the Pyrrhic War Rome allied with Carthage
The North African city state was soon to be its foe in over a century’s struggle for Mediterranean dominance.10. Rome was already a deeply hierarchical society

The Punic Wars
[programme]11. 3 Punic Wars between Rome and Carthage were fought between 264 BC and 146 BC

12. Carthage was a Phoenician city
13. Carthage is about 10km from Tunis, capital of Tunisia
14. The flash point for the wars was the island of Sicily

15. Hannibal’s father, Hamilcar Barca, commanded the city’s forces in the First Punic War

16. Hannibal’s crossing of the Alps took place in the Second Punic War in 218 BC
According to contemporary accounts, he took 38,000 infantry, 8,000 cavalry and 38 elephants into the mountains and descended into Italy with about 20,000 infantry, 4,000 cavalry and a handful of elephants.17. At the Battle of Cannae in 216 BC, Hannibal inflicted on Rome the worst defeat in its military history

18. Hannibal so concerned the Romans that they demanded his personal surrender long after they had defeated Carthage’s armies

19. The Third Punic War (149 – 146 BC) saw Rome achieve total victory over its enemy
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20. Carthage had become an obsession to some Romans, most famously Cato the Elder (234 BC – 149 BC)

Rome’s greatest battles
21. The Battle of Silva Arsia in 509 BC marks the violent birth of the Republic
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22. The Battle of Heraclea in 280 BC was the first of the Pyrrhic victories of King Pyrrhus of Epirus over Rome
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23. The Battle of Agrigentum in 261 BC was the first major engagement between Rome and Carthage

24. The Battle of Cannae in 216 BC was a huge disaster for the Roman army
Hannibal, the great Carthaginian general, surprised everyone by completing an almost impossible land journey to Italy. His brilliant tactics destroyed a Roman army of nearly 90,000 men. Hannibal could not capitalise on his victory with an assault on Rome though, and the massive military reforms the disaster precipitated only made Rome stronger.25. The Battle of Carthage in around 149 BC saw Rome finally defeat their Carthaginian rivals
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26. The Battle of Alesia in 52 BC was one of Julius Caesar’s greatest victories

27. The Battle of the Teutoburg Forest in 9 AD probably stopped Rome’s expansion at the River Rhine

28. The Battle of Abritus in 251 AD saw two Roman Emperors killed
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29. The Battle of the Milvian Bridge in 312 AD is important for its role in the advance of Christianity

30. The Battle of the Catalaunian Plains (or of Chalons or of Maurica) in 451 AD stopped Attila the Hun

Roman architecture
31. Much of the Romans’ architectural mastery is due to their use of concrete
Mixing a dry aggregate with a mortar that would take up water and then harden gave the Romans a range of building materials of great flexibility and strength. Roman concrete is very similar to modern Portland cement.32. The dome of the Pantheon in Rome is still the world’s largest unsupported concrete dome
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33. The Colosseum was Rome’s great games arena
Starting at around 70 AD, it took around 10 years to build over the demolished palaces of Nero, and could hold anything up to 80,000 spectators.34. The Circus Maximus, largely dedicated to chariot racing, was even larger
35. Romans didn’t invent either the arch or the vault, but they perfected both

36. Aqueducts carried water, allowing large cities to grow
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37. Roman sewers are less celebrated but just as vital to urban life

38. The transport of people, goods and above all soldiers relied on Rome’s amazing network of roads
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39. Great structures were an important means of stating Roman power

40. Roman bridges still stand and are in use today

Julius Caesar
41. Julius Caesar was born in 100 BC and named Gaius Julius Caesar

42. When his father died suddenly in 85 BC the 16-year-old Caesar was forced to go into hiding
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43. Caesar was kidnapped by pirates around 78 BC while crossing the Aegean Sea

44. Personal debt from lavish spending troubled Caesar throughout his political career
While governor of part of Spain he changed the laws on debt to protect himself. He often tried to remain in high political office in order to enjoy immunity from private prosecution.45. Caesar ignited civil war by crossing the Rubicon River into northern Italy in 50 BC

46. Caesar never married Cleopatra

47. Caesar adopted a version of the Egyptian calendar, with its solar rather than lunar regulation, in 46 BC

48. At the Triumph to celebrate his victories, two armies of 2,000 people each fought to the death in the Circus Maximus

49. Caesar was married three times, to Cornelia Cinnila, Pompeia and Calpurnia

50. Caesar was killed on 15th March (the Ides of March) by a group of as many as 60 men.

The Triumvirate
51. There were in fact two Roman Triumvirates
[programme] The first was an informal arrangement between Julius Caesar, Marcus Licinius Crassus, and Gnaeus Pompeius Magnus (Pompey). The Second Triumvirate was legally recognised and consisted of Octavian (later Augustus), Marcus Aemilius Lepidus, and Mark Antony.52. The First Triumvirate started in 60 BC

53. Crassus was legendarily wealthy

54. Pompey was a successful soldier and enormously popular

55. The agreement was at first a secret

56. In 56 BC the three met to renew their by then fragile alliance

57. Crassus died after the disastrous Battle of Carrhae in 53 BC

58. Pompey and Caesar were soon vying for power

59. Pompey could have won the war at the Battle of Dyrrhachium in 48 BC
60. Pompey was murdered in Egypt by Egyptian court officials
When his head and seal were presented to Caesar, the last standing member of the triumvirate is said to have wept. He had the conspirators executed.The glory of Rome
61. In the 2nd century AD, the Roman Empire had an estimated population of around 65 million people

62. The period from 96 AD to 180 AD has been labelled the time of the 'Five Good Emperors'
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63. During Trajan’s reign (98 – 117 AD) the Empire reached its greatest geographical extent
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64. Trajan’s Column was built to celebrate final victory in the Dacian Wars of 101 AD to 106 AD
It is one of the most important visual sources on Roman military life. About 2,500 individual figures are shown on its 20 round stone blocks, each of which weighs 32 tons. [programme]65. In 122 AD Hadrian was able to order the building of a wall in Britain 'to separate Romans from barbarians'
The wall was about 73 miles long and up to 10 feet high. Built of stone with regular forts and customs posts, it is an extraordinary achievement and parts of it still survive.66. At its height the Roman Empire covered 40 modern nations and 5 million square km

67. The Empire built great cities
The three largest, Rome, Alexandria (in Egypt) and Antioch (in modern Syria), were each twice as large as the largest European cities at the start of the 17th century.68. Under Hadrian the Roman army has been estimated to have been 375,000 men in strength
[programme]69. In order to fight the Dacians, Trajan built what was for 1,000 years the longest arched bridge in the world
The bridge across the Danube was 1,135m long and 15m wide.70. The Pax Romana (Roman Peace) dates from 27 BC to 180 AD
There was almost total peace within the Empire, law and order was maintained and the Roman economy boomed.A troubled empire
71. 69 AD has been named 'the year of the four emperors'
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72. Nero himself was an appalling emperor
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73. Commodus (ruled 161 – 192 AD) was famously stupid

74. The period from 134 BC to 44 BC is called the Crises of the Roman Republic by historians

75. There were multiple civil wars during the period of the crises

76. 193 AD was the Year of the Five Emperors

77. 'The Year of the Six Emperors' was in 238 AD
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78. Diocletian (ruled 284 – 305 AD) tried to hold the Empire together with a four-man Tetrarchy
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79. Caligula (ruled 37 –41 AD) is generally accepted as Rome’s worst emperor
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80. The Sack of Rome by Alaric the Goth in 410 AD greatly upset emperor Honorius for a moment or two

81. Roman games, called ludi, were probably instituted as an annual event in 366 BC
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82. The Romans probably took gladiatorial games from the Etruscans or Campanians
Like the two rival Italian powers, the Romans first used these combats as private funeral celebrations.83. Trajan celebrated his final victory over the Dacians with games
84. Chariot racing remained the most popular sport in Rome

85. There were four factiones racing, each in their own colour

86. Spartacus (111 – 71 BC) was an escaped gladiator who led a slave revolt in 73 BC

87. Emperor Commodus was famous for his almost-mad devotion to fighting in games himself
Caligula, Hadrian, Titus, Caracalla, Geta, Didius Julianus and Lucius Verus are all reported to have fought in games of some sort.
88. Gladiator fans formed factions too, favouring one type of fighter over others

89. It’s not clear how often gladiatorial fights were to the death
The fact that fights were advertised as 'sine missione', or without mercy, suggests that often losers were allowed to live. Augustus banned fighting to the death to help tackle a shortage of gladiators.90. It has been estimated that 500,000 people and more than 1 million animals died in the Coliseum, Rome’s great gladiatorial arena

The Fall of the Roman Empire
91. The date of the Fall of the Roman Empire is hard to pinpoint
When Emperor Romulus was deposed in 476 AD and replaced by Odoacer, the first King of Italy, many historians believe the Empire was over.92. The 'Fall of the Roman Empire' usually refers to just the Western Empire
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93. The Empire was put under pressure during the Migration Period
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94. In 378 AD Goths defeated and killed Emperor Valens in the Battle of Adrianople

95. Alaric, the Visigothic leader who led the 410 AD Sack of Rome, wanted above all to be a Roman
He felt that promises of integration into the Empire, with land, money and office, had been broken and sacked the city in revenge for this perceived treachery.96. The Sack of Rome, now the capital of the Christian religion, had enormous symbolic power

97. The Crossing of the Rhine in 405/6 AD brought around 100,000 barbarians into the Empire

98. In 439 AD the Vandals captured Carthage

99. After the death of Libius Severus in 465 AD, the Western Empire had no emperor for two years
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100. Julius Nepos still claimed to be Western Roman Emperor until 480 AD
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Image Attribution: France’s decisive defeat to Coalition forces at the Battle of Leipzig (1813) was used to celebrate German military strength in the buildup to World War One. Painting by Alexander Sauerweid.
I find the effect remarkable. I often start speeches with a roundup of the anniversaries on that day. It is odd but it often feels like the events of that distant day in the past have more immediacy, more clarity on the anniversary. Perhaps the vastness of history makes these anniversaries more important.
We cannot hope to remember everything and everyone all the time, so by focusing on the day on which things happened, it is a way of accessing the enormity of the past.
A smorgasbord of historical data
I have amassed a vast amount of data during my career. I am not a period specialist. I have been enormously lucky to make documentaries and podcasts from Greenland to the Falkland Islands and Hong Kong to the Azores. I have a slightly chaotic and sprawling way of collecting the snippets, facts, insights and sources that have fascinated me during that journey.

One what in which I organise it all is by date. I have a huge spreadsheet with much of my data arranged by the day of the year on which the event happened. It is fun to approach it from this direction, and then, at other times, look at it through the prism of location or theme.
I have written On This Day in History in which I use every date of the year to share some of the most important, remarkable, tragic and occasionally bizarre stories that I have stumbled across.
I have written 366 mini essays about completely different parts of history, from the Japanese shogunate to the fall of Troy, Mary Wollstonecraft and the invention of Google. Collectively they tell a story about who and where we are and how we got here.
History is everything that has ever happened to anyone on this planet. There is plenty of it. Every single day in the anniversary of something utterly extraordinary.
On This Day in History by Dan Snow is available to buy now from all good bookshops. You can get a copy of the book for £8.99 at WH Smiths using code ‘Snow18’, or you can buy an annual subscription to History Hit TV and get the book for free.