Rathlin Island Massacre
1575 CE.
Shown on the map at 55.297°, -6.169°.
The Rathlin Island massacre took place on Rathlin Island, off the coast of what is now Northern Ireland, on 26 July 1575, when more than 600 Scots and Irish, retainers of MacDonnells of Antrim, were killed by English Crown forces under the command of Francis Drake and John Norreys.
Text from the Wikipedia article Rathlin Island massacre, licensed CC BY-SA 4.0.