1782 - In Ohio the Gnadenhutten massacre[?] of Native Americans takes place in which 29 men, 27 women, and 34 children were killed by white militiamen in retaliation for raids carried out by another Native American group.
... the left of "=", that will make it a perfect square trinomial of the form x2 + 2xy + y2. Since "2xy" in this case is (b/a)x, we must have y = b/(2a), so we add the square ...