Some 330 suspects are being put on trial in Sincan outside the capital Ankara, and if convicted, they face multiple life sentences over their alleged links to the attempted overthrow of President Recep Tayyip Erdogan.
Over 240 of those named in the indictment are in custody, state-run news agency Anadolu reported.
The suspects, many of them from the Polatli artillery and missile school command in Ankara, have been charged with murder or attempted murder.
The case is being heard at Sincan prison where there was heavy security in place, with a water cannon truck on site and a drone flying overhead as families arrived for the hearing.
Also Read
The courtroom -- which has space for 1,558 people -- was packed with security forces surrounding the suspects as they testified.
The first suspect, a military cadet called Abdulkadir Kahraman, told the court that on the night of the coup, troops had been informed by their commander that there had been a terror attack and were given ammunition.
Ankara has blamed the failed putsch on Islamic preacher Fethullah Gulen -- who lives in self-imposed exile in the United States -- and his movement.
Turkey has denounced the movement as a terrorist organisation and the suspects on trial at Sincan are also accused of belonging to an armed terror group.
The hearing is one of several cases that opened across the country this month, with 47 people going on trial in the western city of Mugla on charges of attempting to assassinate Erdogan.
Following the failed putsch, Ankara declared a state of emergency and began a widespread crackdown, placing more than 43,000 people in pre-trial detention.
The state of emergency remains in place as the trials get under way in the biggest legal process in the country's history.
Disclaimer: No Business Standard Journalist was involved in creation of this content