Factbox: What was Turkey's 'Sledgehammer' trial?

(Reuters) - Turkey’s appeals court upheld convictions on Wednesday of top retired military officers for leading a plot to overthrow Prime Minister Tayyip Erdogan’s government a decade ago in a case underlining civilian dominance over a once all-powerful army.

Here are some details about the so-called “Sledgehammer” plot:

* The alleged Sledgehammer plot dates back to 2003, months after the November 2002 elections, when Prime Minister Erdogan’s Islamist-rooted AK Party won 363 seats in the 550-seat parliament. Its success fuelled speculation that the secularist military, which staged three coups between 1960-1980, could once again intervene in Turkish politics.

* The trial was partly focused on a military seminar attended by the defendants which prosecutors said was part of a plot to oust the government.

* Military commanders were accused of trying to destabilize the government with plans to bomb mosques and trigger a conflict with Greece by shooting down one of Turkey’s own warplanes and planting bombs in Istanbul to pave the way for a military takeover.

* Defendants and their lawyers have said the evidence against them was fabricated, and that a war game used at the seminar had nothing to do with the alleged Sledgehammer plot to overthrow the government, which they maintain was a forgery.

* In September last year, a court in Silivri handed prison terms to more than 300 serving and retired army officers out of some 360 who were on trial.

* In Wednesday’s ruling, the court upheld 20-year prison sentences for chief suspect Cetin Dogan, a former commander of the prestigious First Army, former air force commander Ibrahim Firtina and retired admiral Ozden Ornek.

* Among other leading figures whose convictions were upheld were Engin Alan, a retired general elected to parliament as a member of the National Movement Party in 2011, and retired general Bilgin Balanli, who had been in line to become air force commander before his arrest.

* A separate Turkish court in August jailed a former military chief for life and imprisoned scores of other leading figures in connection with the separate Ergenekon conspiracy to overthrow the government.

(This story is corrected in paragraph six to show defendants say war game was not linked to alleged plot)

Reporting by David Cutler, London Editorial Reference Unit