Complex sentence: Eventually, however, Kasperek and his wife and two daughters became U.S. Citizens, and after Poland became free again, he felt he could finally write the memoir of his adventures, "Kazik's Polish Navy".
Split into simpler sentences: Eventually, however, Kasperek and his wife and two daughters became U.S. Citizens. After Poland became free again, he felt he could finally write the memoir of his adventures, "Kazik's Polish Navy".