BOGOTA (AFP) — Colombia witnessed history at midnight Sunday when the guns fell silent in a 52-year-old war between the State and the Revolutionary Armed Forces of Colombia, the South American country’s largest leftist rebel group.

“The end of the conflict has arrived!” President Juan Manuel Santos exulted on his Twitter account Friday after signing a decree to halt military operations against the FARC, as the rebel group is known.

The measure went into effect at midnight (0500 GMT), five days after the conclusion of peace negotiations that have been underway in Havana since November 2012.

Throughout that period the war continued, with the government refusing a truce for fear that any let-up in the military pressure would enable the FARC to rebuild a force currently officially estimated at 7,500 fighters.

Nevertheless, as the negotiations deepened, the FARC declared a unilateral ceasefire in July 2015, and the government responded by suspending air attacks on the rebels.

The cease fire that went into effect at midnight will be the first in which both sides commit to a definitive end to the fighting.

Peace “begins to be a reality,” FARC leader Rodrigo Londono, better known by the nom de guerre Timoleon Jimenez or “Timochenko”, wrote on his Twitter account.

Colombian media reported that the rebel chief would issue cease fire orders to his troops yesterday from Havana.

“The cease fire is really one more seal on the end of the conflict. It is the test of fire,” said Carlos Alfonso Velazquez, an expert on security at the University of La Sabana. In his view, the end of Latin America’s oldest conflict has been “practically a fact for the past year”.

The last clash between Colombian security forces and FARC rebels was on July 8, according to Cerac, a research group that monitors violence by Colombia’s armed groups.

“The FARC prepared for D-Day,” read the headline on its latest report on the conflict.

Santos and Timochenko will sign the final peace agreement sometime between September 20 and 26, Defence Minister Luis Carlos Villegas said Saturday.

Villegas did not say who would attend or where it will be held, but Santos has said the signing could take place at UN headquarters in New York, or in Havana or Bogota.

The cease fire and definitive end of hostilities will be followed by a six-month demobilisation process in which guerrilla fighters gather at collection points and give up their weapons under UN supervision.

Beginning today, Villegas said, “corridors” will be identified through which guerrillas will move toward 22 zones and six encampments where they will turn in their weapons and begin the process of returning to civilian life.

But before they do, the FARC will convene its leaders and troops one last time before transforming into “a legal political movement”, according to a statement made public on Saturday.

The rebel gathering will be held from September 13-19 in an expanse of grasslands surrounded by jungles near the former guerrilla stronghold of San Vicente del Caguan in southern Colombia.

Attending will be 200 rebel delegates, including the FARC’s 29-member central committee.

International guests and journalists also have been invited to observe the event.

Less than two weeks later, on October 2, Colombians go to the polls to cast ballots in a referendum on the peace agreement.

Approval requires a majority ‘yes’ vote by at least 4.4 million people, or 13 percent of the electorate.

The exact question that will be asked is not yet known.

“We are at the doors of perhaps the most important political decision of our lives,” said Santos, calling on Colombians to vote with hope and without fear.

The Colombian conflict, which has involved other armed groups besides the FARC, still has loose ends. The National Liberation Army, a smaller leftist guerrilla group, remains unreconciled.

But the conflict appears to be reaching an end point, having exacted a fearsome toll: some 260,000 dead, 45,000 missing, and 6.9 million people uprooted from their homes.