1915 – During World War I, German troops used poison gas for the first time, with fatal consequences.
1921- Subhash Chandra Bose resigned from the Indian Civil Service for the independence of the country.
1966 - India's cricket umpire Sundaram Ravi was born.
1970 - The first Earth Day was celebrated and since then, on April 22, World Earth Day is celebrated every year with a different theme.
1977 - On this day, April 21, 1977, for the first time, optical fiber was used for telephonic traffic.
1983: Spacecraft Soyuz T-8 returned to Earth.
2008: Russian President Vladimir Putin was awarded the Ludwig Nobel Prize.
2005: Second Asian-African conference started after 50 years in Bandung (Indonesia).