It all started in 1681. You see, following the reopening of the public theaters in England after the Restoration, Shakespeare's King Lear was occasionally performed, but it apparently wasn't the most popular of the Bard's plays. We have few records of these performances, so perhaps a nation that had just gone through a civil war did not want to see another civil war displayed so bleakly on the stage.
Then in 1681 Nahum Tate wrote an adaptation of King Lear that would have a lasting influence. King Lear, Tate declared was broken, but he knew how to fix it. In his dedication to the new adaptation, Tate wrote:
'Twas my good fortune to light on one expedient to rectify what was wanting in the regularity and probability of the tale, which was to run through the whole a love betwixt Edgar and Cordelia....
That's right. If Shakespeare had really known what he was doing, he would have eliminated the King of France and had Cordelia fall in love with Edgar, who could then save her life just in the nick of time and bring about a happy ending.
Tate went beyond just that, though. He also cut the character of the Fool entirely. (I mean, if he's not very funny, what's he doing there?) And in addition to saving Cordelia and Lear, Tate kept Gloucester alive as well. Sure it was a tragedy, but that didn't mean it had to be such a downer.
Today, we find such changes laughable, but audiences liked the new version, and it was difficult to convince them to go back to the original. In 1756, the great actor David Garrick restored a number of passages Tate had cut from the play, but he still didn't bring back the Fool, and he kept Tate's happy ending.
One could argue that Shakespeare had not left a single authorized version of the play, as in fact there were two versions of King Lear published during and directly after his lifetime. Still, both of these versions have the Fool (whose part is somewhat lengthier in one of the versions) and neither of them have a love story between Edgar and Cordelia. And while the two endings differ somewhat, the basic final catastrophe is the same.
Edmund Kean tried to present the original ending in 1823, but audiences hated it, and he was forced to resume Tate's Act V lovefest after only two performances of the Bard's finale. Three years later, he attempted something similar, but again there was no Fool, and that silly Edgar-Cordelia love story remained.
The hero of our story is William Charles Macready, who in 1838 presented a tragic Lear, with the Fool, and without Edgar and Cordelia as lovers. Macready still kept Gloucester alive, but at last, at the dawn of the Victorian era, there was a King Lear worthy of Shakespeare. Macready would of course go on to rescue other disparaged Shakespearean plays, including King John in 1842.
As much as we might complain about modern directors taking liberties with great plays, it's difficult to imagine someone today trying to turn King Lear in to a feel-good romp. And we at least partially have Macready to thank for that.