B1 battle droids were battle droids that made up the backbone of the Trade Federation Droid Army[3] and the Separatist Droid Army.[4] Often called "Clankers" by Galactic Republic clone troopers,[5] they were the successor of both the HKB-3 hunter-killer droid.[source?] and the OOM-series battle droid.

B1s were perhaps the most numerouso and expendableo 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 Trade Federation. In almost every battle involving the Trade Federation there were B1s.

Early battles involving the droids required a control mainframe for the droids to "think" from, but this was mostly removed post-Battle of Naboo after an attack destroyed the mainframe stationed there, resulting in all the droids on the planet shutting down.

(starwars.wikia.com/wiki/B1_battle_droid)