There's been numerous Bloody Sundays over the years.
Bloody Sunday in Russia, involved a demonstration outside the Tsar's Winter Palace when Russian guards shot the protestors.
The Bloody Sunday described by happyguy above, isn't the first BS in Irish history. After Michael Collins had many Government agents in this country assassinated in the 1920s War of Independance, the British army drove into a Gaelic football ground in a tank and began shooting spectators indiscrimanately.
There were two “Reigns of Terror,” if we would but remember it and consider it; the one wrought murder in hot passion, the other in heartless cold blood; the one lasted mere months, the other had lasted a thousand years; the one inflicted death upon ten thousand persons, the other upon a hundred millions; but our shudders are all for the “horrors” of the minor Terror, the momentary Terror, so to speak; whereas, what is the horror of swift death by the axe, compared with lifelong death from hunger, cold, insult, cruelty, and heart-break? What is swift death by lightning compared with death by slow fire at the stake? A city cemetery could contain the coffins filled by that brief Terror which we have all been so diligently taught to shiver at and mourn over; but all France could hardly contain the coffins filled by that older and real Terror... --- Mark Twain