Complex sentence: Merle's "major achievement" was his 13-book series of historical novels, "Fortune de France" (1977--2003), which recreate 16th and 17th century France through the eyes of a fictitious Protestant doctor turned spy.
Split into simpler sentences: Merle's "major achievement" was his 13-book series of historical novels, "Fortune de France" (1977--2003). Recreating 16th and 17th century France through the eyes of a fictitious Protestant doctor turned spy.