Fifteen years ago, on Feb. 15, 2003, somewhere between 6 million to 11 million people turned out in at least 650 cities around the world to protest the United States’ push to invade Iraq. It was the largest anti-war protest and remains the largest one-day global protest the world has ever seen.

Thousands of anti-war demonstrators, some carrying yellow and black signs reading “U.S. out of Iraq now!” marched on the Pentagon, one of several protests worldwide to mark four years of war.

Ten years ago today, the world saw what was by some accounts the largest single coordinated protest in history. But why was the antiwar movement ignored?

As President Barack Obama formally declared an end to combat operations in Iraq, the anti-war movement that helped sweep him into office — and that worked for seven years to bring U.S. troops home — finds itself struggling for survival.