Cumhuriyet -- which means simply 'Republic' -- was set up in 1924 as a staunch supporter of the secular modern nation created by Mustafa Kemal Ataturk out of the ruins of the Ottoman Empire.
But in the last years it has taken a strong line against the ruling Islamic-rooted Justice and Development Party (AKP), putting it on a collision course with President Recep Tayyip Erdogan.
The 13 journalists and executives convicted include some of the most prominent commentators in Turkey, such as editor-in-chief Murat Sabuncu, celebrated cartoonist Musa Kart and influential anti-Erdogan columnist Kadri Gursel.
They were given multiple sentences for "aiding and abetting terror organisations without being a member" but they remain free pending appeal.
Three others were acquitted.
They had been accused of ties with Kurdish militants and the group of US-based preacher Fethullah Gulen blamed for the July 2016 failed coup, charges that supporters say are ridiculous.
"Enough is enough with this cruelty," Cumhuriyet said in its front page on Wednesday before the convictions.
After the verdict, the newspaper said on its website: "You will be shamed in front of history."
Throughout the trial and during their stints in jail, the staff have remained defiant.
Editor-in-chief Sabuncu said in late 2016: "We bow down in front of our people and our readers. We do not bow down in front of anyone else."
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Unlike many other Turkish newspapers that are owned by big industrial holding companies -- which critics say makes them vulnerable to government influence -- Cumhuriyet is owned by a foundation to ensure its independence, if not financial security.
It has little of the celebrity gossip and snaps of Turkish soap stars on holiday that take up pages of most of its rivals, instead giving greater space to the arts.
Some local and special interest newspapers in Turkey trace their history back to Ottoman times but Cumhuriyet is the oldest of the mainstream national titles.
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It has a circulation of just over 50,000 but its influence as an independent voice had been hugely significant.
A key decision was taken in February 2015 when, after years of internal conflicts, Cumhuriyet appointed the high-profile Turkish writer and filmmaker Can Dundar as its editor-in-chief.
Moving the paper to the left, Dundar took a far more stringent anti-government line and in May 2015 published a sensational front page claiming to show the government sending arms to rebels in Syria.
Erdogan warned Dundar he would pay "a heavy price" and in May 2016 Dundar was handed a five-year-and-10-month jail term for revealing state secrets. His Ankara bureau chief Erdem Gul got five years.
But last month, Turkey's top appeals court quashed the verdict. The Court of Cassation, known as the Yargitay, said he should face an even more serious charge of "providing information for the purpose of espionage" and a longer prison term of up to 20 years.
Dundar was also wanted over the current case against Cumhuriyet but the court on Wednesday ordered his dossier to be separated from the others. But, with his appeal pending, Dundar slipped away to Germany from where he set up a new Turkish-language media organ.
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The paper had also riled the authorities in early 2015 by reproducing a caricature of the Prophet Mohammed in the wake of the attack on French satirical weekly Charlie Hebdo in Paris.
Dundar stepped down as editor in August 2016, saying coming back to Turkey to face the judiciary "would be like putting one's head under the guillotine."
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