Complex sentence: Fishel was a proponent of the anti-colonial, anti-communist third force doctrine in Asia and was impressed with Diệm and helped him organise contacts and meetings in the United States to enlist support.
Split into simpler sentences: Fishel was a proponent of the anti-colonial, anti-communist third force doctrine in Asia and was impressed with Diem. He helped Diem to organise contacts and meetings in the United States to enlist support.