Complex sentence: A sixth officer, 12th Regiment Engineer Commander Capt. Friesenhahn, had been captured but not convicted, as he was found by the court to have done everything within his power to destroy the bridge.
Split into simpler sentences: A sixth officer, 12th Regiment Engineer Commander Capt. Friesenhahn, had been captured. But he was not convicted as he was found by the court to have done everything within his power to destroy the bridge.