Marie and Pierre Curie proved the existence of the new element radium when they chemically isolated one-tenth of a gram of pure radium chloride.

Marie and Pierre Curie were both pioneering scientists in their own right, but as a research partnership they are most famous for their work on radioactivity. Inspired by the work of the French physicist Henri Becquerel who had been the first person to discover radioactivity, the Curies’ work won them the 1903 Nobel Prize in Physics which they shared with Becquerel himself.

Marie had been born and raised in Poland but, since women were not permitted to attend university there, she moved to France to take up a place to study at the Sorbonne in Paris. Having secured degrees in both physical sciences and mathematics by 1894 she married Pierre, an established physicist, whom she had met through a mutual friend. Marie subsequently began to pursue a Ph.D. for which she studied the recently-discovered rays emitted by uranium.

Having coined the term radioactivity to describe the radiation she observed, Curie focused on the minerals pitchblende and torbernite in her search for materials that emitted more radiation than uranium itself. Inspired by his wife’s discovery that the element thorium was radioactive, Pierre dropped his own research in 1898 to work with her. In July they published a joint paper announcing the existence of an element they named polonium, and in December they did the same for radium.

To unequivocally prove their existence, the Curies sought to isolate them from pitchblende. Having processed tons of the mineral, they eventually obtained one-tenth of a gram of radium chloride on 20 April 1902, for which they shared the 1903 Nobel Prize in Physics.

On the 19th April 1770, the British explorer Captain James Cook first caught sight of Australia.  Or at least that’s what the log of HMS Endeavour said.  The problem was, Cook and his crew had been at sea for nearly 2 years, having sailed west from Britain across the Atlantic to South America, and then onwards across the southern Pacific.  By the time they arrived on the south-east coast of Australia, they had – in a calendar – skipped a day.  According to some sources, therefore, Cook arrived in Australia on April 20th.

Irrespective of whether we use the ship’s log or the modern calendar to record the date, the voyage of the Endeavour was significant for being the first European voyage to reach the east coast of Australia.  The Dutch navigator Willem Janszoon was the first to chart the west coast over 100 years previously.

After sighting land, it was another ten days before Cook and his crew actually stepped ashore.  The first sighting had been of Point Hicks, but it wasn’t until the ship had travelled some distance along the coast to what is now known as Botany Bay that Cook and his crew felt they had found a suitable mooring.

Botany Bay is now a major transportation hub, since it is home to Sydney’s cargo seaport and two runways of Sydney airport.  However, for many years the name Botany Bay conjured up different images of transportation since Botany Bay had been the first proposed site for a British penal colony.

Pope Julius II laid the cornerstone of the current St. Peter’s Basilica, one of Catholicism’s most sacred buildings.

St. Peter’s Basilica, whose enormous Michelangelo-designed dome makes it one of the most dominant features on the Rome skyline, is located on what Catholics believe is the burial site of Saint Peter, one of the Twelve Apostles of Jesus Christ.

Emperor Constantine the Great had built an earlier basilica on the site of a shrine that was reputed to mark St. Peter’s burial place in the 4th century. However, this building had fallen into a poor state of repair by the 15th century and in 1505 Pope Julius II made the decision to demolish the 1,100 year old basilica and build an entirely new one.

Such an undertaking would prove to be incredibly costly but, with funds partially provided by the selling of indulgences, construction began on a design by architect Donato Bramante in 1506. A number of adaptations were made to the plans over the next few decades, although a large part of the current building was designed by Michelangelo after he took over the project in 1547.

It took over a century to complete St. Peter’s Basilica, which was consecrated by Pope Urban VIII on 18 November 1626. Judged by many as the greatest example of Renaissance architecture, the basilica is the largest church in the world. Even more than 500 years after its construction, the dome still remains one of the largest in the world and continues to tower over lavish decorations and unmatched pieces of religious art. Yet, despite its position as perhaps the most famous Catholic building in the world, St. Peter’s Basilica is not the mother church. This is rather St. John Lateran, the cathedral church of Rome and the official seat of the Pope.

On the 17th April 1492, the Catholic Monarchs of Spain – Queen Isabella and King Ferdinand – signed an agreement to support Christopher Columbus’ voyage in which he crossed the Atlantic and discovered the Americas.

The Capitulations of Santa Fe granted a number of official titles to Columbus as well as ten per cent of any treasure he was able to secure.  The Capitulations mention the possibility of pearls, precious stones, gold, silver, spices, and – just in case he found anything else – “other objects of whatever kind, name and sort”.

Columbus’ plan was not to reach the Americas.  He was trying to find an alternative route to the valuable spice markets of Asia by sailing West across the open Atlantic, rather than having to navigate around Africa.  The modern belief that people at the time feared he would drop off the edge of a flat earth is a myth, since people had accepted that the Earth was a sphere since the time of the Ancient Greeks.

Columbus’ fleet of three ships set off from the Canary Islands on 6th September 1492.  5 weeks later they landed in what are now the Bahamas.  Despite significant evidence against him, by the time Columbus died in 1506 he still refused to acknowledge that he had not, in fact, discovered the Western route to Asia.  However, he was made Governor of the Indies by the Catholic Monarchs, although they removed him after accusations of cruelty.  The Spanish rulers said that this cancelled the Capitulations of Santa Fe, and so refused to give him to 10% of all profits originally agreed.

Vladimir Lenin arrived in Russia after a decade of self-imposed exile.

Lenin, the leader of the Bolshevik Party, had left Russia in 1907 after Tsar Nicholas II cancelled many of the reforms he had promised following the 1905 revolution. While abroad he remained busy organising Bolshevik groups and publishing Marxist works, but following the February Revolution and the abdication of the Tsar in 1917 he began making plans to return to Russia.

The country had been weakened by the exhausting toll of the First World War and this, combined with disastrous food shortages, had prompted the popular revolt that overthrew the Tsar. In his place the Provisional Government ruled the country, and they opted to continue the war effort despite strong opposition from the Russian people.

German officials were keen to further destabilise the situation. Despite being at war, Lenin and other Bolshevik exiles were granted permission to return to Russia from Switzerland through Germany in a ‘sealed train’. This meant that Lenin and his companions were never legally recognised as being in Germany.

The group then took a ferry to Sweden followed by a second train to Finland, arriving at Finland Station in Petrograd on 16 April. The next day Lenin published the April Theses in which he denounced both the Provisional Government and the First World War, and claimed that Russia was “passing from the first stage of the revolution…to its second stage, which must place power in the hands of the proletariat and the poorest sections of the peasants.”

Less than seven months later the Bolsheviks overthrew the Provisional Government in the October Revolution.

On 15th April 1755, Samuel Johnson published “A Dictionary of the English Language” in London. Johnson was not the first to write a dictionary, but his was the most comprehensive and detailed to date. The finished book contained 42,773 words, each of which featured notes on each word’s usage. Perhaps most astounding is the fact that Johnson wrote the entire dictionary himself, taking 9 years to do so, and earning the modern
equivalent of £210,000 British pounds for his efforts.

Johnson’s book was by no means the first dictionary to be produced – as far as we’re aware that accolade goes to Sir Thomas Elyot, who was the first to publish a book called a Dictionary in 1538 while working for Henry VIII. However, it’s generally accepted that Johnson’s dictionary was the ‘go to’ reference for the English language until the publication of the first Oxford English Dictionary in 1888 – 173 years after Johnson published his.

Despite the impact of Johnson’s dictionary, it would be fair to say that it created a number of problems that the modern English language has inherited. His spellings have become standard, despite them having a number of inconsistencies. However, as Johnson himself wrote in a letter to an Italian lexicographer in 1784, “Dictionaries are like watches: the worst is better than none, and the best cannot be expected to go quite true.”

The future Roman Emperor Titus began the Siege of Jerusalem, during which the Second Temple was burned and destroyed.

The Roman attack on Jerusalem came four years into the First Jewish–Roman War. Triggered by ethnic tensions between Romans and Jews in Judea, the Great Revolt quickly spread throughout the province. Emperor Nero sent four legions, approximately 80,000 soldiers, under the command of his trusted general Vespasian and his son Titus to crush the uprising. By the time Vespasian was recalled to Rome in 69 CE to be appointed Emperor, the Roman forces had driven most of the rebels back to the fortified city of Jerusalem.

Titus moved to besiege the city in early 70 CE, coinciding with Passover. Assisted by the experienced general and former governor of Judea, Tiberius Julius Alexander, he positioned three legions on the western side and a fourth to the east on the Mount of Olives. Pilgrims were permitted to enter the city to celebrate Passover, but the Romans refused to allow them out again. The increase in population placed additional strain on the already-depleted food and water supplies in the city.

Many of the details of the siege were recorded by the Jewish historian Josephus, who had defected to the Roman side after his surrender earlier in the war. Having failed to negotiate with the defenders of the city, but having breached the Third and Second walls, the Romans sought to force the Jews into starvation by erecting a wooden palisade that used every tree in a 10 mile radius.

When the Romans breached the final defences in August the remaining defenders were massacred and the Temple was destroyed, leaving the Western Wall as the only surviving feature.

Late on the 13th April 1970, the spacecraft Apollo 13 was rocked by an explosion from one of its oxygen tanks. The resulting emergency led to the calm announcement by the crew of, “Houston we’ve had a problem”. However, most people misquote the phrase as “Houston we have a problem” after the award winning 1995 film changed the tense. The movie also placed the words in the mouth of Commander Jim Lovell, where in fact it was Command Module Pilot Jack Swigert who first reported the issue.

The explosion occurred after a routine procedure to stop gasses settling in their tanks. An investigation by NASA has since found that a spark from an exposed wire in the oxygen tank caused a fire, leading to an expansion of gasses that eventually blew apart the tank. The explosion ripped off the side of the Service Module, vented oxygen into space, and left the crew stricken in a damaged craft.

Rather than landing on the moon, the mission’s focus was now to bring the crew safely home. Improvisation was key, with the crew forced to turn their landing unit into a lifeboat to ferry them back to Earth before transferring back to the Command Module for reentry. Fortunately the heat shield had not been damaged, and the crew splashed down safely on April 17th.

The Canadian Corps successfully captured Vimy Ridge in the First World War.

Vimy Ridge was a 7km ridge that had been held by the Germans since the Race to the Sea in 1914. French forces had made numerous attempts to seize the ridge over the next two years at the cost of approximately 150,000 casualties. However, due to the need to move French troops to Verdun, in October 1916 the position was taken over by the four divisions of the Canadian Corps.

By early 1917 the war had become one of attrition. Desperate to break the stalemate, French and British commanders planned a major offensive near the city of Arras to divert German forces from the main French offensive further south. The Canadians were tasked with seizing Vimy Ridge, which the Germans had heavily fortified.

The Canadian Corps under the command of Lieutenant-General Sir Julian Byng, and with the assistance of numerous British support units, carefully rehearsed their attack in the preceding weeks. They studied detailed maps and aerial photographs of the enemy lines, laid communication cables, dug a series of tunnels leading directly to the front lines, and stockpiled shells for the enormous artillery barrage that was to precede the assault.

Over 1 million shells were fired at the German lines for a week before the attack. Referred to by German troops as ‘the week of suffering’, the bombardment destroyed many of their defences and left them exhausted. At 5:30 am on 9 April the first wave of Canadian troops advanced behind a creeping artillery barrage through sleet and snow. They captured most of their objectives on the first day, and took control of the final target – a heavily fortified mound known as the Pimple – by nightfall on 12 April.

On the 11th April 1961, the trial of Nazi SS Lieutenant Colonel Adolf Eichmann began in Israel. Eichmann was known as the architect of the Final Solution, the man who coordinated the transportation of Jews from across Europe to Death Camps in the East.

At the end of the Second World War, Eichmann had fled Europe in an attempt to escape being tried for war crimes. Eventually arriving in Argentina with his family, he lived for a number of years under the assumed name Ricardo Klement. However, as one of the world’s most wanted Nazi war criminals, the Israeli secret police – the Mossad – spent years tirelessly searching for him. After being given the tip-off that he may be in Buenos Aires, they eventually captured him and forcibly took him to Jerusalem for trial.

With Eichmann sitting inside a purpose-built bullet-proof glass booth, the trial lasted 16 weeks and exposed for the first time the extent of the atrocities that occurred in the Holocaust. Eichmann’s main line of defense was that he was not personally involved with the killings, and was just following orders. However, on the 15th December 1961, the three judges hearing the case unanimously found him guilty of the 15 charges against him and sentenced him to death. Eichmann was executed by hanging six months later, his body cremated, and his ashes scattered at sea.