Gaius Suetonius Tranquillus,
The Lives of the Twelve Caesars…
“ Not only Curio, but Marcus Actorius Naso as well declare that Caesar made another plot with Gnaeus Piso, a young man to whom the province of Spain had been assigned unasked and out of the regular order, because he was suspected of political intrigues at Rome; that they agreed to rise in revolt at the same time, Piso abroad and Caesar at Rome, aided by the Ambrani and the peoples beyond the Po ”
