Jaynes was a Human male who served as a sergeant in the Republic Army during the Cold War between the Galactic Republic and the Sith Empire. Around the year 3646 BBY, he was stationed on the planet Ord Mantell, where he served at Fort Garnik on the island of Avilatan during the Separatist War fought between the Republic and a group of Separatists. While at the fort, he directed new arrivals to one of the base's combat instructors, Lieutenant Forris. Nearly three years after his arrival on Ord Mantell, Jaynes was still serving on Ord Mantell and was stationed at Fort Garnik, where he met a new recruit of Havoc Squad, a well-known elite squad of Republic soldiers.