R4 courier droids were used to transport information from place to place when computer networks were not available. Courier droids were usually repurposed astromech droids the featured special markings to differentiate them. The Empire did not program their courier droids to have personalities. As a result, courier droids could only beep yes and no.
An R4 courier droid
When Grand Moff Wilhuff Tarkin ordered the destruction of Lothal's Imperial Communications Center in 4 BBY, the Imperial authorities there began using R4 courier droids to physically transport sensitive data. The Spectres took advantage of the situation to try to discover the whereabouts of Kanan Jarrus, stealing a courier droid designated 264 and substituting their own repainted droid, C1-10P. The rebel droid infiltrated an Arquitens-class command cruiser in orbit of Lothal, obtained information on Jarrus' whereabouts before returning to his own ship, the Ghost, which was under heavy fire.
Aboard the Ghost, 264 was making itself useful putting out fires, much to the surprise and approval of the rebel crew. So impressed was the crew that they openly considered making the Imperial droid a permanent member of their crew. The temperamental C1-10P, however, would not tolerate this, and pushed his potential rival out of the cargo doors while the ship was still in flight. On the grasslands below, two Loth-cats were surprised when 264 fell from the sky into their midst. The droid was not destroyed, and righted itself, finding itself in curious company.
On several undercover missions, Chopper was disguised as an R4 courier droid. This enabled Chopper to infiltrate and destroy an Imperial Interdictor in the Del Zennis system in 3 BBY. Later in 2 BBY, Chopper was disguised as an R4 courier droid during a mission undertaken by Hera Syndulla and Ezra Bridger to reclaim a family heirloom, the Syndulla Kalikori, from Grand Admiral Thrawn. Chopper's disguise managed to fool the stormtroopers stationed at the former Syndulla residence and allowed him to plant bombs throughout the building to aid Hera and Ezra's escape.
Chopper destroys an R4 courier droid
The Galactic Empire also stationed several R4 courier droids at the Imperial Armory Complex in Lothal's Capital City. During a mission to infiltrate the factory, Chopper was disguised as a courier droid. To enter Section A2 and steal secret Imperial plans, Chopper electrocuted an R4 courier droid and stole its clearance code. Despite his disguise, Thrawn discovered that an unauthorized C1-series astromech droid had breach the chamber and stolen his blueprints for a prototype starfighter.
The R4 courier droid first appeared in "Rebel Resolve," the fourteenth episode of the canon animated series Star Wars Rebels' first season. More information about the droid was furnished in a Databank entry and Michael Kogge's chapter book Battle to the End, which summarizes the plot of several Star Wars Rebels episodes including "Rebel Resolve." R4 courier droids also appeared in "An Inside Man," the eighth episode of the third season of Star Wars Rebels.
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