B1 battle droids, also occasionally refered to as "Battle-Bots"[source?] were battle droids that made up the backbone of the Separatist Droid Army. Often called "Clankers" by Allied troops, they were the successor of both the HKB-3 hunter-killer droid.[source?] and the OOM-series battle droid. B1s were perhaps the most numerous—and expendable—soldiers in galactic history, and, unlike most organic soldiers, they were capable of action in hostile environments such as underwater or in space. They were designed, for the most part, to defeat their enemies through sheer numbers, not through their ability to think (they were very vulnerable to tricks) and utilize combat skills (unlike clone troopers). The B1 battle droid was frequently used as a soldier for the Confederacy of Independent Systems. As a result, B1s were present in nearly every battle involving the Confederacy of Independent Systems.