Complex sentence: Plutarch, The Life of Pompey, 17 Pompey's proconsular mandate was extra-legal, as a proconsulship was the extension of the military command (but not the public office) of a consul.
Split into simpler sentences: Plutarch, The Life of Pompey, 17 Pompey's proconsular mandate was extra-legal. A proconsulship was the extension of the military command (but not the public office) of a consul.