Complex sentence: The Baltic War is a sequel to both the first-of-type sequels, "Ring of Fire" and "1633", it had to await schedule co-ordination by the two authors, which proved difficult and delayed the work by nearly two years.
Split into simpler sentences: The Baltic War is a sequel to both the first-of-type sequels, "Ring of Fire" and "1633". It had to await schedule co-ordination by the two authors, which proved difficult and delayed the work by nearly two years.