Short answers, pulled from the story.
The Greek Civil War began in March 1946 when a group of 30 ex-ELAS members attacked a police station in Litochoro village. The conflict officially ended on the 16th of October 1949 when KKE leader Nikolaos Zachariadis announced a temporary ceasefire preventing complete annihilation.
Markos Vafiadis took command of the Democratic Army of Greece from a base in Yugoslavia after being sent by the Communist Party leadership. Aris Velouchiotis previously led the ELAS High Command before his death in May 1945 while Stefanos Sarafis served as military chief for that earlier organization.
At least 80,000 people died in the civil war leaving Greece divided for ensuing decades. More than 25,000 children were forcibly taken to Eastern Bloc countries during the war according to UN Special Committee reports.
US President Harry S. Truman announced the United States would step in to support the Greek government against Communist pressure beginning in early 1947. This intervention marked the start of a long troubled relationship where US ambassadors advised the king on important issues including prime minister appointments for several decades.
The Democratic Army of Greece lost due to the bitter split between Stalin and Tito which demoralized ranks within the KKE when Soviet Union broke relations with Yugoslavia in June 1948. General Alexander Papagos launched Operation Pyrsos in August 1949 resulting in heavy losses that made it impossible for DSE forces to sustain resistance pitched battles.