Upon the foundation the Black Panther Party for Self-Defense in 1965, Huey Newton and Bobby Seale envisioned a society without corruption and oppression that they perceived from police and the government. They outlined their goals and beliefs in their Ten-Point Platform (further detailed on the vision page). However, their methods of working toward this society soon became violent.
The Civil Rights Movement, at the time of the foundation of the party, was being led by Dr. Martin Luther King, Jr. and the black community of Birmingham, Alabama. The vision of these groups was to create change in the United States through peaceful measures. Newton and Seale did not agree with this philosophy. They believed that the use of peaceful measures would only permit police and the American government to continue to oppress and segregate. They viewed the use of violence to be the most effective method of protest and retaliation against what they saw as a corrupted society. Fear, they believed, was the most powerful method of communication for the civil rights cause.
The first and most famous violent act of the Black Panthers was the killing of Officer John Frey on October 28, 1967. Newton was arrested and put on trial for murder, where he pleaded temporary insanity. His arrest sparked a national campaign which came to be known as the "Free Huey" movement. The Free Huey movement involved Americans of all races and ages, but the main demographic was black college students and other young adults. However, many white Americans also joined the movement. While the number of "Honkies for Huey" was small, they contributed to the recognition of the Black Panthers as a legitimate organization.
While the original vision of the Black Panthers didn't completely include the knowledge of the violent measures the group would take to accomplish their goals, the events of October 1967 definitely led to a series of riots and other violent events over the following fifteen years that contributed to gaining the reputation as the violent group they culminated to be. Not to indicate whether these violent acts were a positive or negative thing, they certainly did contribute to making the Civil Rights Movement the historical phenomenon it is.