I stumbled across an Oregonian article on the fantastic Portland history Tumblr, PDX Tales, proving that May Day rallies (and shindigs at Chapman Square) have always been tumultuous in Portland. Titled "Socialists To Be Peaceful May Day" (library link), the article explains May Day ralliers' interest in occupying Chapman Square, much to the dislike of the police. Sound familiar?
But this time, the police's main beef was based on slightly different rules: At the time, Chapman Square was only accessible to women and children. Neighboring Lownsdale Square was the man park. Unlike the ongoing Occupy protests, these ralliers seemed to begrudgingly give in to the police force with little protest. Here's the article's opening paragraph:
"The crowds which will probably assemble at the Plaza blocks this afternoon to witness a battle royal between the police and the Socialists are in for a great disappointment. Instead of being “innocent bystanders” in the casualty list of a general riot, they will, if the plans of the revolutionists work out, be benevolently assimilated and towed in the rear of the procession to Seventh and Market streets, where Socialist oratory will be flung to the four winds throughout the afternoon. Thus all probability of serious disturbance in Portland on this international annual festival day of unrest is removed."