With their familiar domed heads, the R4 astromechs served similar functions as their R2 brethren. They worked as mechanics, fixing up broken and battered Starfighters, but they also operated as faithful co-pilots.
One R4 in particular, R4-G9 (nicknamed Geenine) by chance found herself in the midst of some of the most tumultuous moments in "Star Wars" history. She was on the Starfighter that Obi-Wan Kenobi flew to Naboo, where Anakin Skywalker climbed aboard.
Kenobi didn't always have an R4 by his side, though. He zoomed into the Battle of Coruscant with an R4-P17, which was shot and ruined by a buzz droid attack.
Geenine stepped (or rather, wheeled) into the fray. She accompanied Kenobi to Utapau in the Outer Rim, where he hoped to locate and permanently dismantle General Grievous. Instead, Kenobi was nearly assassinated by supposedly friendly clone troopers and he was forced to escape the locale in another ship, leaving Geenine behind. What is it with these Skywalker people abandoning their droids, anyway? So much for appreciation.