April 13th

On this day - April 13th 1919 - Over 300 Indians were killed in the Jallianwala Bagh massacre

Jallianwala Bagh massacre, also known as the Amritsar massacre, was a massacre of over 300 peaceful protesters in Punjab, India. The people was gathered in an large open area to celebrate the Baisakhi festival. The protesters were fired on for 10 minutts by the British army, and the main fire was directed at the protesters who were trying to escape. At least 379 people died and 1100 people were inured in the incident, but the number might have been much higher. The incident led to the Non-cooperation Movement of 1920–22 in India.

The area a few months after the massacre 

September 5th

On this day – 5th of September 1972 – The  Munich Massacre

In 19772 hosted the German city Munich the XX Olympic summer games. In the  second week of hosting, on September 5th, was 11 Israeli Olympic participants taken as hostages by a Palestinian group known as “Black September”. The five hostage-takers had entered the participant’s village during the night, and although several of the Israel weightlifters put up a fight, they did not stand a chance against the AKM rifles. The hostage-takers demanded the liberation of Palestinian prisoners in Israel. Israel refused. Sadly, all 11 hostages, five of their hostage-takers and one German police officer were all killed in the days the hostage situation lasted and the rescue attempt which ended the conflict.

By High Contrast - Own work, CC BY 3.0 de, https://commons.wikimedia.org/w/index.php?curid=19948068