Shooting the Peacemaker
Israel reeled in shock when Yigal Amir, an extremist Jewish settler, shot dead Prime Minister Yitzhak Rabin on November 4, 1995. Somehow, this once implacable foe of the Arabs had come to an understanding with Israel's chief bogeyman, Yasser Arafat, the Chairman of the Palestine Liberation Organisation. It seemed that a long-elusive peace between Israel and the Palestinians might be possible. But, following Rabin's death, the peace process became bogged down.

Could Rabin have steered Israel to peace with the Palestinians if he had lived? There was much dividing the two sides. In truth, Rabin and Arafat were merely at the beginning of what would have been a long and difficult process. But, if Rabin was anything, he was tenacious. And few Israeli leaders since have matched his popular appeal. Many people, in the Middle East and beyond, have pondered the Yitzhak Rabin "what if?" scenario.

A Stolen President
As Robert Kennedy lay fatally wounded in a hotel service corridor on June 5, 1968, liberals were already beginning to mourn the lost opportunity his assassination represented. Many analysts are convinced that Kennedy, although he had entered the race for nomination late, would have become the Democratic Party's presidential candidate if Palestinian immigrant Sirhan Sirhan had not shot him dead.

With Kennedy up against Richard Nixon for president in 1968, the "what if?" scenario really takes flight. Nixon had already failed against John F. Kennedy and would have struggled against JFK's charismatic younger brother. Robert Kennedy as president would have taken the United States out of Vietnam earlier and introduced several liberal laws. What's more, no Nixon in the White House means no Watergate - still the worst scandal to have blighted the U.S. presidency. Americans lost a lot when they lost Robert Kennedy.

An Inconvenient Revolutionary
There were many thorns in Joseph Stalin's side but none was as irritating or as persistent as Leon Trotsky. The pair's rivalry began in the early 1920s when Stalin out-manoeuvred Trotsky in the battle to succeed Vladimir Lenin, Russia's first Soviet leader. In 1929, Trotsky was deported and became the anti-Stalinist left's figurehead. He continued campaigning over the next decade until his assassination by Ramon Mercader, a Stalinist agent, on August 20, 1940.

There was little chance that, had he lived, Trotsky could have returned to the Soviet Union to challenge Stalin. But he was an embarrassment. His Fourth International was detracting from Stalin's official organisation devoted to world revolution, the Comintern. And he was working on a biography of Stalin. If Trotsky had lived to push through publication of the book (it was suppressed for several years following his death), Stalin would have faced international criticism much earlier.

After the Fuhrer
The case of Adolf Hitler poses a different kind of "what if?" What if Colonel Claus Schenk von Stauffenberg had succeeded in killing the Nazi dictator on July 20, 1944? Stauffenberg's co-conspirators - senior officers in the regular army - had plans to trigger a full-scale coup against the Third Reich if Hitler had died. What would have happened if the army had taken control of Germany?

Stauffenberg and his colleagues weren't bleeding heart liberals. But some of them, at least, were disgusted by the Nazis' brutality. And they were realists. Germany was by this time fighting on three fronts and was not expected to win the war. Would the generals have sued for peace to avoid Germany's total destruction? We'll never know. What's painfully clear is that, with Hitler still alive, no one would be seeking peace. Millions more would die.