Bloemfontein - The alleged rightwing Mangaung plotters also planned to take over a railway line, the Bloemfontein High Court heard on Tuesday.
State witness Jaco Scherman testified that the group wanted to steal ammunition, destroy a railway control centre in Kimberley, and then take over the railway lines manually.
He said part of the plan was to attack SA National Defence Force ammunition depots in De Aar, Jan Kempdorp and Naboomspruit.
He said Mark Trollip, who pleaded guilty to a charge of conspiracy and was sentenced to eight years in prison last year, informed them that he had established a non-governmental organisation and rented several railway houses between De Aar and Victoria West in the Northern Cape.
Scherman said these houses were to be used to store the stolen ammunition after the depot attacks.
He said there was a plan to take control of the railway line manually as the railway control centre would be destroyed.
The ammunition would then be transported in special railway vehicles - that could drive on roads and on railway lines.
Treason accused Johan Prinsloo, 51, looked relaxed during the testimony.
Scherman is the second State witness to testify in the trial.
Prinsloo faces charges of treason, conspiracy to take part in terrorist acts, and possession of illegal ammunition.
Prinsloo, Trollip, 48, and Martin Keevy, 49, were arrested in connection with an alleged plan to attack the African National Congress's Mangaung conference on December 16, 2012.