It seems that the first March 8 demonstrations were held on this day in 1913, with women all across Europe marching for peace. There had been some attempts earlier to create an International Working Women's Day by the incipient feminist movement but it was this event which started the tradition, later revived in the 1960s.
Working women's demonstrations on this day in 1917 were one of the main triggers of the Russian Revolution, and hence the festivity became official in the USSR.
8 March 1932 Soviet poster
Today women across the World still use this day to meet each other and state their demands. It is not yet a holiday in most countries though. It should.
8 March 2010 Basque demo (Gasteiz)
In this little country today, the major unions have stated that the draconian "reforms" promoted by the FMI, EU and local capitalists (with total subservience of the "socialist" government and parliament majority) are to only cause more precariousness among working women, already a very discriminated sector.
The struggle continues. Today like a century ago social justice remains to be implemented.