Complex sentence: On 31 August in 1959, he was proposed to Colonel General rank, but he refused because of professing himself lacking moral and not deserving the position, then eventually was promoted to the rank of Lieutenant General.
Split into simpler sentences: On 31 August in 1959, he was proposed to Colonel General rank, but he refused because of professing himself to lack moral and not deserve the position. He eventually was promoted to the rank of Lieutenant General.