Some websites claim that Internation Women's Day in on March 8th to celebrate a famous strike by female textile workers in New York.
e.g.: Woman Aid:
1857 The first recorded organised action by working women anywhere in the world took place in New York on March 8, 1857, when hundreds of women in the garment and textile factories staged a strike in protest of low wages, long working hours, inadequate pay, inhumane working conditions and the lack of the right to vote.
Or even this book:
On March 8, 1857 women in the garment industry marched through New York City to protest their 12 hour a day sweatshop working conditions. Many were beaten by police. Two years later, again in March, they formed their own union.
Wikipedia's International Women's Day entry has a different explanation about why March 8th was choosen.
There was no specific strike happening on March 8, despite later claims
Was there a major protest in March 8th, 1857?