The Rain Expeditionary Force (abbr. REF) was a Konoha assault force formed by the Third Hokage to set the battlefront in the Land of Rain during the Third Great Shinobi War. However, the force was ambushed while traveling to the border, and was nearly wiped out. Only by the efforts of Shikaki Nara did the force survive the attack. The expedition force, after receiving reinforcements to replenish lost manpower, was able to discover a launch point for a possible invasion of Konohagakure. With the help of several expeditionary forces sent to help, the REF was able to drive the Rock ninja out of Konoha territory.