Wikipedia:Selected anniversaries/April 13
April 13: Thai New Year's Day.
- 1598 – King Henry IV of France (pictured) issued the Edict of Nantes, allowing freedom of religion to the Huguenots.
- 1873 – In the wake of a contested election for local political offices in Colfax, Louisiana, USA, armed white supremacists overpowered freedmen and the African American state militia trying to control the parish courthouse, killing over 100 of them.
- 1919 – British Indian Army troops opened fire on a peaceful gathering in Amritsar, Punjab in India, killing hundreds of unarmed men, women and children.
- 1943 – World War II: Germany announced the discovery of a mass grave of Polish prisoners-of-war executed by Soviet forces in the Katyn Forest Massacre.
- 1984 – Indian forces launched a preemptive attack on the disputed Siachen Glacier region of Kashmir, triggering a military conflict with Pakistan.