An excerpt about the Communist-led violence in Hollywood in the late 1940's, from Peter Schweizer's Reagan's War: The Epic Story of His Forty Year Struggle and Final Triumph Over Communism:
Herb Sorrell had promised violence if he didn't get his way in the studio strike, and it didn't take him long to deliver. Led by his "sluggers," strikers smashed windshields on passing trains and threw rocks at the police. One studio employee went to the hospital after acid was thrown in his face. When the police tried to break up the melee, things got even worse. As actor Kirk Douglas remembered it, "Thousands of people fought in the middle of the street with knives, clubs, battery cables, brass knuckles, and chains."
Sorrell and his allies wanted to shut down the studios entirely, so anyone who crossed the picket line became a target of violence. Jack Warner insisted on keeping up production and the studio remained open. To avoid injury, workers, including stars who were shooting movies, were forced to sneak into the studio lot through a storm drain that led from the Los Angeles River.
Reagan, getting ready to start production on Night Unto Night, was furious about the violence. And unlike his approach to the little battle with the Communists in HICCASP, he was not in the mood to retreat.
Blaney Matthews, the giant-sized head of security at Warner Brothers, had seen this sort of violent strike before. He advised Reagan and other stars to use the storm drain to get onto the lot safely. Reagan flat out refused. If he was going to cross the picket line, he was going to cross the picket line, he told Matthews.
Matthews then arranged for buses to shuttle Reagan and a few others through the human gauntlet outside the studio gate. But he offered a bit of advice: Lie down on the floor, or you might get hit by a flying Coke bottle or rock. Again Reagan refused. Over the next several days, as he went to the studio lot to attend preproduction meetings, a bus would pass through the human throng of violent picketers, with a solitary figure seated upright inside.