Few events change the course of history as drastically as assassinations. Both those that succeed and those that fail, as was recently the case with Slovakia's Prime Minister Robert Fico. These violent acts have altered the destiny of nations and have left an indelible mark on the collective report .

We will explore some of the most significant assassinations in recent history. Some are relevant for what they reveal; others, for what they still conceal.

Certain assassinations mark the tragic end of a long history of conflicts and rivalries. This is the case of Leon Trotsky, murdered at his residency program in Coyoacan, Mexico. In the summer of 1940, Trotsky was brutally beaten with an ice axe by Ramon Mercader, a young communist under the orders of the NKVD.

Pushed by his mother, Charity, Ramon had gained the confidence of Trotsky's closest circle. Mercader approached the Bolshevik leader under the pretext of showing him a article he had written, and taking advantage of the distraction, pulled out an ice axe hidden under his coat and hit Trotsky on the head.

Despite efforts to save him, Trotsky died the following day due to the severity of his wounds. Trotsky's assassination culminated a long history of infamy, a devastating blow to the world left that confirmed Stalin's omnipotent power to eliminate his opponents and the iron will to dominate the USSR.

Similarly, the assassinations in recent Spain reveal the complexity of governing a country marked by chronic instability. It is often overlooked that five presidents lost their lives in Spain at the hands of assassins. Three were shot by anarchist gunmen: Canalejas, Eduardo Dato and Cánovas del Castillo. In the same period, Alfonso XIII suffered up to five frustrated assassination attempts. Although the monarch saved his skin, his subjects did not suffer the same fate: on his wedding day, a bomb aimed at the royal carriage would end the lives of 28 innocent people.

The only death from the period immediately prior to the Restoration is that of Prim, whose authorship is still unknown.

All these deaths marked a not so distant period in our history in which social tensions, as well as political ones, were at their height. Although perhaps the most spectacular -and unexpected- was that of Franco's right-hand man, Admiral Carrero Blanco, by the still young and practically unknown ETA.

To a certain extent, these assassinations can be framed within a previous spiral of violence. This would be the case with Tsar Nicholas II after the Bolshevik triumph in the Russian revolution, Mahatma Gandhi in the period of violence that followed India's independence, or Egyptian President Anwar el Sadat after the signature of a peace with Israel.

However, there are other assassinations that, unexpectedly, produce an earthquake in history. Such is the case of John F. Kennedy, shot on November 22, 1963 in Dallas. In spite of the multiple investigations carried out, there are still many gaps in the research and unanswered questions. The KGB secret services themselves were shocked by the president's death, fearing possible incrimination.

But the assassination did not lead to a major confrontation with the Russians: the official report of the Warren Commission, published in 1964, concluded that Lee Harvey Oswald acted alone in the Kennedy assassination. Although officially a closed case, questions still remain about the accuracy of the evidence presented, the validity of testimony, the withholding of evidence, and the possibility that Oswald had been a patsy.

Kennedy had also been a ruthless politician, full of lights and shadows. The CIA's attempts against Cuban dictator Fidel Castro are well known. Since the files were declassified in 2007, we know of the 638 assassination attempts with which the U.S. secret services tried to put an end to his life. Fidel holds the Guinness record for assassination attempts thwarted by the most ingenious methods: from explosive mollusks to neoprene vests sprayed with poison.

Kennedy's worst crime, however, took place in Vietnam. In one of the most infamous acts of treason in recent history, JFK authorized the violent overthrow of the government of South Vietnamese President Ngo Dinh Diem. In the fall of 1963, just weeks before Kennedy's assassination, the CIA orchestrated a coup d'état that would end the life of the Catholic Diem, the last president with authority over the South Asian country.

The consequences of this power vacuum would be felt soon after, with the escalation of tension that would lead the United States to escalate the most terrible war in its history.

Undoubtedly the most discussed assassination in history happened 110 years ago, on June 28, in Sarajevo. Many historians, from Margaret MacMillan to Christopher Clark, have wondered what would have happened in a world where Archduke Franz Ferdinand had never been assassinated. In this alternative scenario, there would have been no need for the rulers in Vienna to threaten Serbia, no need for Russia to come to Serbia's defense, no need for Germany to back Austria, and no need for France and Britain to honor their treaties with Russia to initiate hostilities.

In this counterfactual history, the war would not have taken place. The Austro-Hungarian Empire would still reign over a mosaic of cultures and ethnicities. Tsarist Russia would not have crumbled so quickly, and the October Revolution would have failed miserably.

The Ottoman Empire might have survived a little longer, long enough to modernize thanks to the construction of railroads and oil refineries.

The leader of the Bolsheviks, Vladimir Lenin, would continue to do what he liked best: write inflammatory pamphlets and retire periodically to sanatoriums to rest from his nervous breakdowns.

Adolf Hitler would never have entered the military or politics. Instead, he would have thrived as a landscape or family portrait painter in a prosperous and happy Austria.

Of course, Jews would continue to thrive without the trauma of the Holocaust and the small Jewish settlement in Palestine would continue to exist, but without the massive influx of refugees, who would remain a minority community in the region.

Yizak Rabin, another great leader assassinated in our time, would have been born in Ukraine, and he would never have needed to push for the Oslo accords to solve the Israeli-Palestinian conflict.

Of course, without the World Wars, scientific advances would have taken a different course: America would not have landed a man on the moon, the atomic bomb would not exist, and the development of penicillin and antibiotics would be much slower. This, however, is just history fiction.