By Daren Butler
ISTANBUL (Reuters) - The conviction of more than 250 people on conspiracy charges may be seen by supporters of Prime Minister Tayyip Erdogan as a triumph for Turkish democracy, but for many the landmark rulings have exposed deep divisions over the country's political future.
A court on Monday jailed a former military chief for life and imprisoned scores of other retired officers, journalists, academics and opposition politicians for plotting to overthrow Erdogan's Islamist-rooted government.
The trial laid bare an underlying tension in Turkish society reaching back to the 1920s when Mustafa Kemal Ataturk forged a secular republic from the ruins of an Ottoman theocracy, curbing Islam's role in public life and sowing the seeds for the military to establish itself as guardian of the new order.
The verdicts after a five-year trial closed a chapter on Erdogan's efforts to stamp out what he has described as "anti-democratic forces", clipping the wings of a military that carried out three coups from 1960 to 1980 and pressured an Islamist-led government from office in 1997.
Yalcin Akdogan, one of Erdogan's top advisers, said the trial was a turning point for Turkish democracy and would be a deterrent to any future thoughts of army intervention.
"Turkey has succeeded with a judicial settling of accounts," Akdogan wrote in the Star newspaper. "With this verdict there was a wholesale conviction of military coups."
Prosecutors had described the "Ergenekon terrorist organization", to which the 275 defendants were accused of belonging, as a network of secular nationalists who pursued extra-judicial killings and bombings to trigger a military coup.
Cynics questioned whether the "Ergenekon" network ever existed, seeing the case as a show trial meant to symbolize Erdogan's taming of the generals. For pro-government media, Monday's verdicts were proof enough.
"Yes, they tried to stage a coup. Life sentences for 19 putschists," said the front page of the pro-government Sabah newspaper above photos of the nineteen, many of them retired top military officers.
The sentences come weeks after street protests against Erdogan's perceived authoritarianism, action sparked by plans to redevelop an Istanbul park which spiraled into an unprecedented show of defiance against his government.
For his critics, the verdicts only reinforced their belief that Erdogan is bent on muting opposition. The main opposition party described them as "illegitimate".
"These are courts which are under the orders of political power and implement its orders, they do not distribute justice," Republican People's Party (CHP) leader Kemal Kilicdaroglu said.
The Turkish military said in a statement it "shared the sadness" of convicted former comrades and their families.
The Ergenekon case was initially welcomed in Turkey as an effort to rein in the country's "Deep State" - an underground network of nationalists with links to organized crime long believed to have been pulling the strings of power.
But concern grew as the trial dragged on about the lengthy detention of defendants and restrictions on their defense.
Perhaps sensing the public unease, parliament passed a government reform abolishing the special courts used to hear conspiracy cases a year ago, although existing trials including Ergenekon were allowed to reach completion.
Sedat Ergin, a commentator with the mainstream Hurriyet daily, said it was difficult to conclude that justice had been done, with 23 different cases merged into one manifestly political trial.
"However much the investigation at the start was founded on just and legitimate grounds, there are sufficient reasons to think there are many defendants who suffered injustice as a result of these verdicts," Ergin said.
The secularist Cumhuriyet daily contrasted heavy sentences imposed on academics and journalists, including its former correspondent Mustafa Balbay jailed for 35 years, with the release of defendants accused of links to an attack on the Council of State court in 2006 in which one judge was killed.
The most controversial verdict was the life sentence imposed on General Ilker Basbug, Erdogan's own former chief of staff. Erdogan himself said in February it was "unforgivable" to describe Basbug as a member of a "terrorist" organization.
The appearance of a leading fighter from Kurdish militant group the Kurdistan Workers Party (PKK) - considered a terrorist organization by Turkey, the United States and European Union - as a prosecution witness in the trial, testifying against the military, further heightened sensitivities.
The leader of the opposition Nationalist Movement Party, Devlet Bahceli, said Basbug's conviction was "judicial murder".
"It would be unnatural for the national conscience to accept and approve a trial process where a PKK ringleader is heard as a witness, tarnished evidence is used and documents and information manipulated," Bahceli said in a statement.
With an election cycle beginning next year, and criticism of the Ergenekon trial potentially providing political capital for the opposition, the government is keen to focus attention instead on how the case has banished an era of military intervention and furthered Turkish democracy.
"Such trials will only have a positive contribution to the normalization of military-civilian relations," Akdogan said.
Just last month, parliament amended an article of the armed forces charter cited by generals in the past to justify coups. The military's duty to "protect and watch over the republic" was replaced with a more limited obligation to defend "the Turkish homeland against foreign threats".
(Additional reporting by Ayla Jean Yackley; Editing by Nick Tattersall and Sonya Hepinstall)