Apr. 21. 1972: Protesters in El Paso, Texas, pelt Gen. Westmoreland with tomatoes. 2001: Sixty thousand or more dance, shout, and battle police on the streets of Quebec City, where 34 Western Hemisphere heads of state gathered to negotiate the NAFTA-style Free Trade Area of the Americas.

Apr. 22. 1970: An estimated 20 million participate in anti-pollution demonstrations across the US to mark the first Earth Day. Corporate sponsorships were notably absent.

Apr. 23. 1992: Ten thousand Indians march for recognition and reform, Quito, Ecuador.

Apr. 24. 1971: Largest ever (over 1,000,000) demonstration opposing US war in Southeast Asia, Washington DC. 150,000 march at a simultaneous rally in San Francisco.

Apr. 25. 1974: "Carnation Revolution" ends 48-year military dictatorship, Portugal. 1983: One hundred seventy-five women arrested for marching to mourn the rape of women in war, Sydney and Melbourne, Australia.

Apr. 26. 1953: Radioactive rain falls on Troy, New York. 1986: Worst known nuclear disaster in history occurs at Chernobyl, USSR (now Ukraine). Explosion kills at least 200 and irradiates much of Eastern Europe and Scandinavia. Subsequent death toll from radiation exposure is now estimated in the hundreds of thousands.

Apr. 27. 1997: Seventeen activists protesting continued funding of the School of the Americas are arrested for digging a mass grave on Pentagon grounds. 2001: Former senator and presidential candidate Bob Kerry admits he gave orders to execute 13 civilians at Thanh Phong, Vietnam, in 1968, and covered up the war crime for the following 33 years. Liberals rush to commiserate with his mental anguish and applaud his honesty and courage in coming forward, just ahead of a considerably less flattering news account of the incident.

Apr. 28. 1977: Mothers hold first rally for the disappeared at Plaza de Mayo, Buenos Aires, Argentina.

Apr. 29. 1858: Publication in France of P.J. Proudhon's "Justice," with the memorable line, "Property is theft!" 1894: Jacob Coxey's protest Industrial Army of the Poor reaches Washington DC. He led a group of 500 unemployed people from the Midwest, and was arrested for trespassing on Capitol grounds.

Apr. 30. 1970: Announcement of secret US bombing and invasion of previously neutral Cambodia prompts demonstrations at college campuses across the US. Four days before Kent State, National Guard troops fire shotguns on protesters at Ohio State University in Columbus, injuring seven.

May 1. 1971: Beginning of five days of anti-war May Day protests in Washington, DC, resulting in over 14,000 arrests--the largest mass civil disobedience in US history.

May 2. 1911: First worker compensation law in US enacted in Wisconsin. 1968: Despite the murder of Martin Luther King, Jr., his Poor Peoples' March on Washington DC begins, led by successor Ralph Abernathy.

May 3. 1968: Students take over Northwestern University (Evanston, Illinois), demanding African-oriented curriculum. 1981: In Washington DC, 100,000 protest US intervention in El Salvador.

May 4. 1970: Four students killed, 15 others wounded when National Guard opens fire on anti-war demonstration at Kent State Univ., Ohio. 1989: Thirty thousand students march for democracy to Tiananmen Square, Beijing, China.