Rhythm of War is an epic fantasy novel written by American author Brandon Sanderson and the fourth book in The Stormlight Archive series. It was published by Tor Books on November 17, 2020. Rhythm of War consists of one prologue, 117 chapters, 12 interludes and an epilogue. It is preceded by Oathbringer. It is currently both the longest Sanderson novel and longest in the series at 455,891 words, though Oathbringer has a higher page count.

Brandon Winn Sanderson is an American author of high fantasy and science fiction. He is best known for the Cosmere fictional universe, in which most of his fantasy novels, most notably the Mistborn series and The Stormlight Archive, are set. Outside of the Cosmere, he has written several young adult and juvenile series including The Reckoners, the Skyward series, and the Alcatraz series. He is also known for finishing Robert Jordan's high fantasy series The Wheel of Time. Sanderson has created several graphic novel fantasy series, including White Sand and Dark One.