Huey P. Newton was the cofounder of the Black Panther Party for Self Defense. The Black Panther Party at its height in 1969 had around 10,000 members but accurate numbers impossible to prove.
The Black Panther Party was created 1966, The BPP borrowed their Panther logo from Stokely Carmichael and Lowndes County Freedom Organization because Newton loved the "bold logo and courageous organizing".
The BPP was dissatisfied with the failure of other organizations to directly challenge police brutality. They decided to take matters into their own hands and began exercising of their legal right to carry arms while monitoring and observing police behavior in their neighborhoods. (California law that permitted carrying a loaded rifle or shotgun as long as it was publicly displayed and pointed at no one)
As awareness of the Black Panther Party for Self-Defense grew rapidly. On May 2, 1967, the California State Assembly Committee on Criminal Procedure convened to discuss the "Mulford Act", which would make the public carrying of loaded firearms illegal. Newton put together a plan to send a group of 26 armed Panthers to Sacramento to protest the bill. Assembly sessions are open to the public but the public is not allowed on the assembly floor. After Panthers reached the door to the assembly floor, they were quickly ejected.
This Protest by the Panthers led to the quick passage of the Mulford Act but also put the Black Panther Party firmly on the radar of J. Edger Hoover and the FBI. By 1969, The Black Panthers and their allies had become primary targets of COINTELPRO.