Yes, the phrase "All for one and one for all" is indeed from "The Three Musketeers" ("Les Trois Mousquetaires"), a historical novel written by Alexandre Dumas. The novel was first serialized from March to July 1844 and later published as a book.

The motto is associated with the camaraderie and unity of the three musketeers—Athos, Porthos, and Aramis. It reflects their commitment to supporting each other and facing challenges together. The phrase has since become a symbol of teamwork, solidarity, and mutual support.