Every year we observe May Day or International Labour Day to celebrate the contribution of the workers for a better building of the infrastructure and economy on a global scale. Here is the history of May Day (Compiled By Akhila Chandran) | AP
It was the international federation of socialist groups and trade unions which decided to observe May 1 as International Labour Day. This was in commemoration of the Haymarket Riot in Chicago (1886) | Wikipedia
The Haymarket Affair was a violent confrontation between police and labour protesters that broke out in 1886 in Chicago against unfavourable working conditions. The workers who were required to work for 12 hours, took to the streets demanding an 8-hour shift from their side.
Several police officers and demonstrators were killed and scores injured. Many labour leaders were tried and convicted of murder. Four of them, including Spies, were hanged | AP
The Soviet Union leaders embraced the new holiday and believed it would encourage workers in Europe and the US to unite against capitalism. The fall of the USSR saw May Day celebrations waning across Europe.
The first labour day was celebrated in India on 1 May 1923, in Chenna by the Labour Kisan Party of Hindustan.