rights leader In his capacity as NAACP advisor, Groppi organized an all-Black male group called the Milwaukee Commandos. They were formed to protect marchers and help quell violence during the "Freedom Marches." With the NAACP Youth Council, Groppi mounted a lengthy, continuous demonstration against the city of Milwaukee on behalf of fair housing. He led these fair housing marches across the 16th Street Viaduct (since renamed in his honor) spanning the Menomonee River Valley. The half-mile wide valley was considered to be a symbolic divide for the city. Throughout this period, he received both physical and moral support from human rights activists like Dick Gregory and Martin Luther King Jr. Though Groppi was denigrated and arrested on numerous occasions for standing firm in his beliefs, he was instrumental in dramatizing the segregated housing situation in Milwaukee. These efforts led to enactment of an open-housing law in the city. In 1966 Groppi acted on common knowledge in the Milwaukee area that most judges and elected officials belonged to the Fraternal Order of Eagles, which at the time did not admit people of color to its membership. He questioned how a judge who was a member of an organization that did not welcome African-Americans as members could rule impartially in cases involving African-Americans. He organized pickets at the homes of some of the member judges, most notably Circuit Court Judge Robert Cannon, despite the fact that Cannon was a liberal and had voiced opposition to the Eagles' membership policies. These demonstrations continued, on and off, until 1967. During this period, Groppi also worked for passage of legislation which would outlaw discrimination in the buying and renting of homes (in 1968 such a law was passed on the federal level, known as the Fair Housing Act). In 1968 Groppi was awarded the Pacem in Terris Peace and Freedom Award by the Davenport Catholic Interracial Council. It was named after a 1963 encyclical by Pope John XXIII that called upon people of good will to secure peace among all nations. Pacem in terris is Latin for "Peace on earth". On September 29, 1969, Groppi organized and led the "Welfare Mothers' March on Madison," during which over 1,000 welfare mothers marched into Wisconsin's State Assembly chamber, seizing it in protest against planned welfare cuts. Groppi and his supporters held the State Assembly chamber in a sitdown strike for 11 hours before police recovered the chamber.