FARC, Colombia's biggest rebel movement, will sign a historic peace accord with the government on Monday aimed at ending a war that has lasted five decades and killed 220,000 people.

The pact will be signed by Colombian President Juan Manuel Santos and a rebel fighter known by the alias Timochenko, in the city of Cartagena, in a process that took more than four years to finalise.

Fifteen South American presidents, UN Secretary-General Ban Ki-moon and US Secretary of State John Kerry, are scheduled to witness the signing ceremony.  More than 2,500 guests have been invited to wear white as a sign of peace, and Santos will add his signature to the 297-page accord with a pen made from a recycled shell used in combat.

The signing ceremony will not officially close the deal, though. Colombians are being given the final say on endorsing or rejecting it in an October 2 referendum. 

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Opinion polls point to an almost-certain victory for the "yes" vote, but some analysts warn that a closer-than-expected finish or low voter turnout could bode poorly for the many challenges the country faces implementing the ambitious agreement.

Under the terms of the deal, rebels who lay down their weapons and confess to rights abuses will be spared jail  and allowed to provide reparations to their victims by carrying out development work in areas hit hard by the conflict. 

The government has also committed itself to addressing unequal land distribution, which has been a long-standing FARC demand harkening back to its roots as a peasant army in 1964, and the administration has agreed to work with the rebels to provide alternative development to tens of thousands of families that depend on the cocaine trade. 

'Extorting and killing'

FARC-Colombia Timeline

1964:  FARC established as an armed wing of Communist Party

1999-2002: Government and FARC hold peace talks which ultimately fail. During this time FARC control up to 30% of the country 

2008:  The group suffers a series of setbacks. Venezuela's Hugo Chavez urges  the US to stop treating the group as "terrorists".

2012:  Start of peace talks in Havana, co-sponsored by Cuba and Norway

Al Jazeera's Allessandro Rampietti, reporting from the southern town of San Vicente Del Caguant, in what was once known as the "sanctuary" of the rebels, said that much had changed in the town. 

"It is a centre of commerce, crime is down, and the FARC stopped extorting money. Sandbags still block the entrance to the police station, but the trenches that surrounded city hall are gone." 

San Vicente Del Caguan's Mayor Humberto Sanchez, of the conservative Centre Democratic party, which opposed the talks, said that locals were wary. 

"I’m not against the peace process but I’m worried that the FARC will not honour the agreement," he told Al Jazeera.

"During the process they kept extorting and killing people. When you are in a peace process you have to stop committing crimes. But if they do comply with it they’ll have my support."

Among the most controversial parts of the agreement is an attempt to judge the potential war crimes of both rebels and government forces.

 The ceremony in the town of Cartagena, is expected to be charged with symbolism [Reuters]

If the referendum is passed, FARC's roughly 7,000 fighters will start moving to 28 designated zones where over the next six months they are meant to turn over their weapons to UN-sponsored observers.

Analysts say the rebels were forced to the negotiating table after being pushed to the edge of Colombia's vast jungles by a decade-long, US-backed military campaign that claimed the lives of a number of its top commanders.

Negotiations, which had been expected to take a few months, stretched over more than four years.

The process was fraught with challenges, from the military's killing of FARC's then top commander, known as Alfonso Cano, shortly after he authorised a secret backchannel with the government to the rebels capture of an army general who until a few months ago was a trophy prisoner.

The National Liberation Army (ELN), Colombia's second largest rebel group, said on Sunday that its fight with the goverment would stop until the referendum. ELN leaders have previously expressed their wish to engage in their own peace process with the Colombian government. 

Source: Al Jazeera And Agencies