It tells the life of D'Artagnan from his beginnings as a musketeer (1625) to his death as a marshal in Maastricht (1673).
The three novels are :
Twenty Years After part was serialized from January to August, 1845.
Finally there was the substantial The Vicomte de Bragelonne (serialized from October 1847 to January 1850), covering events in the 1660s. In the English translations the final large volume is usually subdivided into three, four or even five individual books, of which the final volume, The Man in the Iron Mask is most well known.