THE HAGUE, Netherlands — Twenty years after Serb forces unleashed a brutal campaign of ethnic cleansing in Bosnia, their military commander, Ratko Mladic, finally is going on trial on charges of masterminding atrocities throughout the country’s devastating 1992-95 war.

Mladic will enter the U.N.’s Yugoslav war crimes tribunal today a frail 70-year-old, a far cry from the swaggering general who commanded Serb forces during the war that left 100,000 people dead.

“I don’t have to tell you how important it is that finally this trial can start 17 years after the first indictment was issued (against Mladic),” said the court’s Belgian chief prosecutor, Serge Brammertz.

For years after the war Mladic was a fugitive and one of the world’s most-wanted men.

His time on the run ended last year when Serbian forces arrested him near Belgrade.

He has been waiting for his trial in the same jail as his former political leader, Radovan Karadzic, who was arrested in 2008 and is now at the midway point of his own trial on charges almost identical to those of Mladic.

Both men are accused of leading Bosnian Serb forces responsible for atrocities that started with a brutal campaign of ethnic cleansing in 1992 and climaxed in July 1995 with Europe’s worst massacre since World War II, the slaughter of some 8,000 Muslim men and boys in the northern enclave of Srebrenica.

They also are charged in the deadly campaign of sniping and shelling during the 44-month siege of the capital, Sarajevo.

The man seen as the overall architect of the Balkan wars of the 1990s, former Yugoslav President Slobodan Milosevic, died of a heart attack in his cell in 2006 before tribunal judges could deliver verdicts in his trial.

Survivors of the Bosnian war hope that will not happen to Mladic, who suffered at least one stroke while in hiding and has been in ill health in The Hague.

“Victims are afraid that Mladic could die, and that would be very disappointing for the victims in Bosnia. I want a verdict for Mladic so that the whole world will see that he is a war criminal and has committed the crimes in Bosnia,” said Kadefa Mujic, 42, from Srebrenica, a representative of the group Mothers of Srebrenica.

Munira Subasic was in Srebrenica on those fateful days in 1995, seeking sanctuary with thousands of other residents in a U.N. peacekeepers’ compound.

She said she still remembers Mladic barking threats at the base’s Dutch commander and ordering men to be separated from women.

“Surrender your weapons and I will guarantee you life,” he told the Bosnian Muslim men and boys, some as young as 11.

“You can survive or you can disappear.”

It was those who obeyed who disappeared, as their bodies still are being found in mass graves scattered around the town.

Thousands who refused managed to flee through the hills to freedom.

After meeting several victims’ groups, Brammertz said they have been a driving force behind the tribunal’s work.