There was one in Russia in 1905 but the most well known one (at least here and if Google 'hits' is to go by) happened in Derry in 1972. There were a few others in Ireland too.

I think the term was added to most retroactively years later. There was one in Dublin in 1920 where the British Army opened fire at spectators at a football game and another in 1921 where the British Army killed 16 people and burnt out hundreds of homes in the Catholic parts of Belfast.

I duno I think the British liked to do bad trout on Sundays.