The most common droid model within the B-series line of Battle Droids, the B1 Battle Droid was most notably used as the foot soldiers of the Confederacy of Independent Systems during the clone wars.
The successor of the OOM-series battle droids, the B1 model appears near identical to their predecessors, but boast the improvement of their independence from an external droid computer due to their individual artificial intelligences. However, although a typical B1 Battle Droid displayed unquestioning obedience to their superiors, they are generally unintelligent and heavily reliant on commands from others due to their inability to effectively strategise. The B1 Battle Droid displays a similar appearance to the Geonosians, likely as this species was responsible for their design and mass production. Typically armed with an E-5 blaster rifles, B1 Droids are also capable of utilising machinery intended for use by humanoid lifeforms, including military vehicles such as the Armoured Assault Tank (AAT) or Multi-Troop Transport (MTT). The B1 Battle Droid is largely comprised of a cheap and mildly durable metal which, although provides some protection, renders them quite fragile in comparison to other battle droids. As such, their primary advantage over an organic army (such as Clone Troopers) would be overwhelming numbers.
in the year 32 BBY, the Neimoidian Trade Federation enacted a blockade around the planet Naboo in protest of the Galactic Republic's taxation of their trade routes. During this time, Viceroy Nute Gunray, acting on instructions from the Sith lord Darth Sidious, launched an invasion of the planet utilising a droid army primarily comprised of OOM Battle Droids. Although the droids were proven successful against the Human and Gungan populations of the planet, they were deactivated when the orbiting control ship was destroyed, severing their connection to a controlling droid computer and shutting them down. This would lead to the B1's independence from such a system in order to remove such a major weakness.
Ten years afterwards, the recently formed Confederacy of Independent Systems, an alliance of planetary systems and species seceding from the Republic, mass produced several models of battle droid to fight in their armies against the Republic, which countered this with the use of an army of clones created by the Kaminoans from the Mandalorian bounty hunter; Jango Fett. The B1 Battle Droid remained the most commonly utilised droid in the Separatist army.
At the end of the Clone Wars, the Sith lord Darth Vader transmitted a shutdown order to the entire droid army after assassinating the Separatist leaders, permanently deactivating almost every droid in the CIS army, and the use of Battle Droids became outlawed by the newly formed Galactic Empire. However, a number of B1 droids remained active even after this. General Kalani, a Super Tactical Droid, blocked the order from reaching the droids under his command as he suspected it of being a Republic trick. Notoriety was also received by a heavily modified B1 Battle Droid known as "Mr. Bones", whose mind was eventually transferred into a BX Battle Droid Commandos.
- Despite being designed to be inexpensive and disposable pawns, B1 Battle Droids have displayed independent thought and emotion, albeit limited. Over the course of the Clone Wars, B1 droids have been seen conversing with one another and have at times displayed fear at overwhelming odds (such as Jedi Knights) and even mild admiration for their enemies at the sight of "impressive" actions. Mr. Bones was also notable for being highly sadistic, as he was often heard singing while killing others.