April 13
1204
Constantinople falls to the Crusaders of the Fourth Crusade, temporarily ending the Byzantine Empire.
1250
The Seventh Crusade is defeated in Egypt, Louis IX of France is captured.
1909
The Turkish military reverses the Ottoman countercoup of 1909 to force the deposal of Sultan Abdul Hamid II.
1919
Jallianwala Bagh massacre: British troops massacre at least 379 unarmed demonstrators in Amritsar, India. At least 1200 wounded.
1939
In India, the Hindustani Lal Sena (Indian Red Army) is formed and vows to engage in armed struggle against the British.
1941
Pact of neutrality between the USSR and Japan is signed.