Complex sentence: After the ravages of the war the nationalists and communists fought in the Greek Civil War (1945--1947), after which the Greek government used the island to exile about 13,000 communists.
Split into simpler sentences: After the ravages of the war the nationalists and communists fought in the Greek Civil War (1945-1947). Subsequently, the Greek government used the island to exile about 13,000 Communists.