A historic midnight ceasefire on Sunday is set to end a 52-year-old war between the Colombian state and rebels belonging to the Revolutionary Armed Forces of Colombia (FARC).
Hundreds of thousands of Colombians have died since 1964 as rebel armies and gangs battled in the jungles in what is considered Latin America's last major civil armed conflict.
The FARC on Sunday issued the order for its fighters to observe the cease fire from midnight.
"I order all our commanders and units and each one of our combatants to definitively cease fire and hostilities against the Colombian state from midnight tonight," top FARC leader Timoleon Jimenez said in a declaration before the media.
"The end of the conflict has arrived!" Colombian President Juan Manuel Santos wrote on his Twitter account Friday, after signing a decree to halt military operations against the FARC.
The measure goes into effect following the conclusion on Wednesday of peace negotiations under way in Havana since November 2012.
Peace "is beginning to be a reality," Jimenez, whose real name is Rodrigo Londono, wrote on Twitter.
The FARC declared a unilateral ceasefire in July 2015. But Sunday night's ceasefire is the first in which both sides have committed to a definitive end to the fighting.
"The ceasefire is really one more seal on the end of the conflict. It is the test of fire," said Carlos Alfonso Velazquez, a security expert at the University of La Sabana.