Here’s a look at some interesting events that took place on this day in history:

1170 – Thomas Becket, Archbishop of Canterbury, is assassinated inside Canterbury Cathedral by knights acting on the orders of King Henry II (More info)

1851 – The first YMCA in the US opens in Boston, Massachusetts (More info)

1890 – In the tragic final chapter of America’s long war against the Plains Indians, the US Cavalry kills 146 Sioux Indians at Wounded Knee, South Dakota (More info)

1937 – The Irish Free State is replaced by a new state called Ireland with the adoption of a new constitution (More info)

1940 – London suffers its most devastating air raid when Germans firebomb the city, killing almost 200 civilians (More info)